A delegation of Yellow Shirt activists from Thailand arrived in Phnom Penh on Sunday to assist in the defence of seven Thai nationals, including a parliamentarian, arrested for trespassing in Banteay Meanchey province last month.

The group includes former senator Karoon Sai-ngam, lawyer Natapom Toprayoon and university professor Walwipha Charoonroj, as well as several Thai journalists. The group are scheduled to meet with the defendants today at Prey Sar prison.

“We want to talk to the seven prisoners so they can plan more what they are going to do,” Karoon told reporters in Phnom Penh yesterday. “We hope the Cambodian government and prison will cooperate … resolving in a fair way that can be better off for both countries.”

The group said they planned to meet with the prisoners’ defence lawyers and officials from the Thai Embassy during their visit. A trial date has not yet been set in the case.

Panich Vikitsreth, a lawmaker from Thailand’s ruling Democrat Party, was questioned in Phnom Penh Municipal Court last week along with his co-defendants, including former Yellow Shirt leader Veera Somkwamkid. The group has been charged with illegal entry and unlawfully entering a military base, charges that carry a combined maximum sentence of 18 months in prison.

Foreign Ministry spokesman Koy Kuong said the government had granted permission for a group of 11 Thais to visit Prey Sar prison on Monday.

“I don’t know what colour they are, red or yellow, but we allowed them to visit at 10am on Monday,” Koy Kuong said.

Suchart Lainamngern, an MP from Thailand’s Red Shirt-aligned Puea Thai party, said on Saturday that former Thai prime minister Thaksin Shinawatra was willing to assist in the case if necessary, the Bangkok Post reported.

Thaksin, who lives in self-exile to avoid a prison term for corrruption, made headlines in Thailand and Cambodia in 2009 when he accepted a controversial appointment as an economic adviser to the Cambodian government.

Thai premier Abhisit Vejjajiva, a rival of Thaksin, condemned the appointment, and the countries downgraded their diplomatic relations before restoring them in August following Thaksin’s resignation from the position.

But despite the offer, Koy Kuong said there was no scope for intervention of any sort at this point in the proceedings.

“Since this case is under the court’s jurisdiction, we will let the court do its work,” he said.