SEOUL - North Korea publicly executed 13 women and two men for illegally entering neighbouring China in search of food, an aid group said Wednesday.

The South Korean group Good Friends, which works in the North, said the 15 were shot on a bridge in Juwongu district in the northeastern town of Onseong on February 20 as local residents watched.

Officials at Seoul's unification ministry, which handles relations with the impoverished hardline communist North, could not confirm the report. Good Friends said in a newsletter the North Korean group had been arrested for illegally crossing the border into China or for helping others to do so, largely to get economic help from relatives there.

"The shooting was too much," one resident was quoted as saying. "All those people did it for their livelihood. They got too harsh punishment."

A female resident was quoted as saying: "Everyone is anxious about a lack of food. The shooting has made people angry."

Good Friends, citing an unidentified local official, said the execution aimed to deter a surge of people illegally crossing the border this spring. "It has become a daily routine for a few residents to disappear and illegally cross the border to visit relatives in China... we shot them to send a warning to people over this," the official said.

Good Friends said unauthorised border crossings are normally punishable with jail terms. The North raised the penalty from three years to a maximum seven years in early 2007, it said.

North Korea suffers severe food shortages and some residents of frontier provinces cross the border to secure supplies before returning. Others try to flee their homeland through China. Rights groups estimate there are tens of thousands of North Koreans hiding out in northeast China.

The refugees often travel on to Southeast Asian countries in the hope of winning eventual resettlement in South Korea.