Thousands of Cambodia National Rescue Party supporters marched through the heart of Phnom Penh yesterday to deliver a petition signed with the thumbprints of more than two million aggrieved citizens to the United Nations.

The march was the culmination of the first day of a three-day opposition protest that, like the petition, will continue to call for an independent investigation into election irregularities and label the government “illegitimate”.

Speaking outside the office of the UN High Commissioner for Human Rights yesterday, party leader Sam Rainsy said the United Nations had pledged to send all the petitions – 84 boxes of which had been carried into the local office from the back of a flatbed truck – to the US for safekeeping.

“They told us they will send all the petitions to the main head office in New York to ensure the security of the petitions. They will take care of them as undeniable evidence,” he said.

Rainsy added that the party would collect another 1.3 million thumbprints, pledging to take the total to 3.3 million of Cambodia’s close to 15 million people.

UN rights representative Wan-Hea Lee said yesterday, however, that she “would only be able to confirm that a petition has been brought to our office”.

Prior to the march, observers estimated that up to 20,000 demonstrators flooded into a festival-like Freedom Park yesterday morning, after countless trucks carrying in jubilant protesters arrived from throughout the country.

The flags of Australia, the US, the UK, Japan, Indonesia and other signatories to the 1991 Paris Peace Agreements fluttered throughout the crowd, reminding onlookers that the purpose of the protest was to call on the international community to pressure the government to abide by the spirit of those accords.

The primary focus of the 1991 agreements, which were signed in the presence of the UN secretary-general, was to bring peace to Cambodia, though it also established the mandate for the UN-sponsored elections that followed and laid down principles for a new, democratic constitution.

Prime Minister Hun Sen said last month, however, that the accords were now invalid, given the country adopted a new constitution in 1993 and had its own sovereign laws.

The UN was nonetheless the first stop on the CNRP’s international petition agenda, with embassies representing other signatories to be visited today and Friday.

Despite protesters disobeying every stricture set by City Hall – a 10,000-person limit at Freedom Park, a 6pm curfew for the event and a 1,000-person march – authorities remained markedly calm yesterday.

Gone were the seemingly endless roadblocks that had infuriated Phnom Penh residents during the CNRP’s past demonstrations, with only a smattering placed around Independence Monument and Hun Sen’s house.

Notably, only two dozen military police and police officers followed the mass of protesters as they marched down Street 51 from Freedom Park to the UN office on Street 302 in Boeung Keng Kang 1 commune. Although streets perpendicular to Street 51 were blocked by police, only a couple of unarmed officers manned the barricades as the demonstrators swept past and waving residents lined the streets.

The masses were finally stopped on the corner of Street 302 by police, with only a few hundred people allowed to continue the final 100 metres to the UN office.

As the protesters returned to Freedom Park, however, hundreds of military police clad in riot gear gathered in the park opposite the prime minister’s house in an apparent act of intimidation, though far fewer flanked the fences immediately next to the opposition supporters.

Khieu Sopheak, spokesman for the Ministry of Interior, said that as the CNRP had breached its agreement with authorities, it was fortunate no serious incident had occurred.

“It is very good there is no violence, but it is regretful that some demonstrators tried to get past police barricades at the Independence Monument. We applaud that there was no violence,” he said.

According to Sopheak, several demonstrators tried to breach barricades as party leaders paid their respects at the statue of slain union leader Chea Vichea on Sihanouk Boulevard while returning from the UN office.

Ou Virak, president of the Cambodian Center for Human Rights, said he believed that police had finally learned that if people “can go about their daily lives” during protests, there is less risk of incident.

“It tells me that the police have learned a bit from the previous main incidents [and] protests.… It tells me the police are maturing a bit and learning to behave in a democracy where people do have the right to protest,” he said. “In a democracy, people protest. It’s normal and police need to be equipped and trained to handle that. That’s just a fact of life.”

Council of Ministers spokesman Phay Siphan agreed that both the government and protesters were learning.

“Both parties, the protesters and the authorities, learn from past experience. Authorities are learning to deal with protesters with discipline. [This] is a new culture for Cambodia,” he said.

Minister of Information Khieu Kanharith said via email that he “[hoped] that everybody could show some maturity in dealing with the issue”.

With the party planning on following a multi-stop route between different embassies today and Friday, policing could prove more complicated.

But in a sign that authorities may be just as well prepared, the Phnom Penh Municipality has issued a public notice on exactly what streets the marches will take place on and during what times over the next two days.

“The City Hall appeals to all citizens to remain calm and patient. Traffic should be avoided on these designated roads that the CNRP will use in order to maintain security, public order and facilitate congestion,” it says.

Streets 61, 47 and 76 will be used from 8-10:30am today, while streets 51, 294 and a number of main boulevards will be used from 8am-12pm Friday, according to the notice. Opposition leaders yesterday also pledged their cooperation with authorities during the demonstrations, saying they would take responsibility for any provocative protesters.

At Freedom Park, elderly Cambodians were a common sight among those who had made the trip into Phnom Penh from the provinces, with many telling tales of past grievances they blamed on the ruling party.

Ma Yin, an 86-year-old grandmother who had travelled from Mondulkiri, said she wished to find justice for her children, who had lost land to an economic land concessionaire, as well as for the voter disenfranchisement she suffered at July’s election.

“It’s not difficult, and it’s not hot,” she said, despite the almost 35-degree temperature.

“We must claim back and find my lost vote and make sure we know where [and how] it was lost.”

Many others were eager to explain that they were present at the demonstration not just for themselves but for numerous others in their families or communities who couldn’t make it due to financial difficulties, work or simply fear.

“My family don’t come because they are scared…they were warned [away],” Lina, a fiery 33-year-old from Kampong Cham said.

“There are millions of them [like that] out there that are supporting people here [today].”