Nineteen foreigners were among those killed in a stampede at a Halloween event in Seoul, South Korea's fire department told AFP on October 30.

The national fire agency said the death toll from the accident had risen to 151 people, including the 19 foreigners, who died in a crowd surge and stampede which happened at about 10pm on October 29.

The fire agency could not immediately provide details of the nationalities involved, but the Yonhap news agency reported that it included people from Iran, Uzbekistan, China and Norway.

South Korean President Yoon Suk-yeol declared a period of national mourning on October 30, saying the government would pay for the medical care of those injured and the funerals of those who died.

"In the centre of Seoul, a tragedy and disaster occurred that should not have happened," Yoon said in a national address.

The disaster occurred in the capital's Itaewon district, where local reports said as many as 100,000 people – mostly in their teens and 20s – had gone to celebrate Halloween, clogging the area's narrow alleyways and winding streets.

Of the dead, 97 were female, said Choi Seong-beom, head of the fire department in Yongsan, which includes Itaewon, Yonhap reported.

Choi said 82 people were injured including 19 seriously, although the Ministry of Interior said 150 people had been injured.

The stampede, the deadliest in South Korea's recent history, happened in a narrow downhill alley near Hamilton Hotel, with eyewitnesses describing scenes of panic as people "fell like dominoes", Yonhap reported.

"A short person like me could not even breathe," one female eyewitness told Yonhap. "It looks like people in the middle suffered the most," she said.