HARBIN - Police in Northeast China's Heilongjiang province are investigating the assault of a couple who were forcibly evicted from their countryside home four weeks ago, local authorities said Thursday.

Qu Longhua and his wife were attacked by five masked men who, with axes and bricks in hand, broke into their home in Sanhe village in the city of Qiqihar around 7 pm on March 24, a spokesman from the city's public security bureau said.

He said the couple were hospitalized for several days but have been discharged. "Police have launched an investigation and we will punish whoever is found responsible for the attack," the spokesman said.

While the spokesman did not say how seriously the couple were injured, photos posted on the web by their daughter, a student at a university in Southwest China's Sichuan province, show Qu with a bleeding face and his wife with swollen cheeks.

Over the past weeks, their daughter has poured out her family's grievances on Weibo.com, a popular Twitter-like microblogging service.

"I promise to do all I can to bring justice to my parents," said the girl, who uses the screenname "rabbit loves yogurt."

She said her parents were previously told to move out of their home in order to make way for a development project.

"They refused to move out in time like most of their neighbors, because the compensation offered by the development company was too low and the new flat they were promised was too small, as they need extra space to keep their farming equipment," the daughter said.

She said her father remembered one of the assailants telling him "this is what you get for remaining here," indicating that the development company may have been behind the attack.

Ten days before the incident, a bulldozer drove into a community in Harbin, capital of Heilongjiang province, with a gang of more than 20 masked men who forced their way into several homes, hauled out the occupants and forcibly demolished the houses.

The use of land for urban and property development has proven a thorny issue in many parts of China, with some companies engaging in hasty land grabs and forced evictions.

Last year, the central government banned such acts in a circular that instructed local authorities to stop the forcible occupation of land and the demolition of homes against their owners' will.