North Korean defectors warned Monday that some 30 refugees in China risked severe retribution if they are sent back, as they joined US lawmakers in urging Beijing to halt plans for repatriation.

Activists fear that China will soon send North Koreans who recently fled the impoverished state back over the border and say that they could suffer abuse or even execution for leaving during mourning for late leader Kim Jong-Il.

Hoping to step up pressure on Beijing, the US Congressional-Executive Commission on China invited two North Koreans who resettled in the United States. They gave accounts of beatings, forced labor and food deprivation when China earlier repatriated them.

"I know that these 30-some refugees are feeling the same dread and terror," said Han Song-Hwa, who recalled how five members of her family of eight died of starvation and abuse.

"The United States government should forcefully raise this issue and pressure the involved people of the Chinese government so that repatriation will not occur."

Campaigners have also started a petition to urge against the North Koreans' repatriation. More than 167,000 people had signed on website change.org as of Monday afternoon.

Han said that she first fled North Korea in 1998 when police tried to evict her hungry family from its village as punishment after her husband crossed into China and brought back a sack of rice.

China sent her back four times before she eventually made it to the United States in 2008. She said that North Korean police would declare the repatriated citizens to be "dogs" and order them always to look at the ground.

"The prisoners are handcuffed and chained to one another, and if the slightest noise is made, the prisoners are beaten with rifle butts," Han said.

Han said that she was forced to work from 5:00 am until night and then take part in "self-criticism" until 11:00 pm, with only a "fist-size" ball of corn and rice to eat each day.

"I was beaten so severely that my skull still has pieces of bone embedded in my head," Han said, adding that she also remains hard of hearing in one ear due to a separate beating that ruptured an eardrum.

Han's daughter Jo Jin-Hye said that repatriated women suffered particular abuse. She recalled that one North Korean agent yelled at a pregnant woman that she was a "bitch who carried Chinese seed."

"He then proceeded to torture and beat her with steel hooks by hitting her on the side and the head, and forcing her to sit and stand repeatedly 500 times until she collapsed," Jo said.

The UN refugee agency UNHCR has urged China not to send the North Koreans back, while a parliamentary committee in South Korea -- the destination for most refugees from the North -- last week passed a resolution criticizing Beijing's policy.

China considers North Koreans to be economic migrants and not refugees deserving protection. Beijing is the main economic and political backer of the isolated state.

Representative Chris Smith, co-chairman of the Congressional-Executive Commission on China, said that China was violating the 1951 UN Refugee Convention and its 1967 Protocol that bar the return of people who have a well-founded fear of persecution.

Smith, a Republican from New Jersey, also called on President Barack Obama's administration to link treatment of refugees to its decision last week to deliver 240,000 metric tons of food aid to North Korea.

The Obama administration agreed to provide nutritional assistance aimed at pregnant women and young children in a deal in which North Korea pledged to freeze its nuclear program and allow back UN inspectors.