Beijing - An international human rights group on Monday condemned China's detention of a housing activist who was due to be released over the weekend, saying it was the latest attempt by Beijing to assert control during the Olympics.

Ye Guozhu, 53, was supposed to be released on Saturday after completing his four-year prison sentence for protesting against the Beijing government's forced eviction of his family in 2003 to make way for Olympic-related construction.

Ye's family was informed by Beijing's Chaobai Prison on Thursday to not bother going to the prison to pick him up as he had been taken away by the Xuanwu branch of the Beijing Public Security Bureau.

Ye's brother, Ye Guoqiang, said the police informed the family on Saturday that his brother is under criminal detention for suspicion of gathering a crowd to disturb public social order.

"The arbitrary detention of Ye Guozhu after completion of his four years sentence demonstrates the extreme measures the Chinese authorities will resort to in order to maintain social control during the Olympics," said Human Rights in China's executive director Sharon Hom.

"This should be a wake-up call to the international community to address the human costs of the Olympics lock-down underway by the Chinese authorities," Hom said.

In the run-up to the August 8-24 Games, Beijing has jailed several dissidents or put them under house arrest or surveillance, while banning petitioners who want to seek redress for injustices from the capital.

Ye Guoqiang told Deutsche Presse-Agentur dpa that the family does not believe his brother is guilty of the latest charge, questioning how he could gather a crowd while in one of China's tightly controlled prisons.

"We can't understand how they could keep him locked up after he has already suffered so much in these four years," said Ye Guoqiang, who had previously said his brother was physically abused in detention.

"We think this is very unfair and inhumane," he said, adding that Ye's 84-year-old father was looking forward to seeing his son and the family does not know how to break the news to him.

The Ye family are well-known critics of the massive redevelopment of Beijing which forced hundreds of thousands of residents to move out of often prime property in central parts of the city to make way for construction that often was not related to Olympic venues.

Beijing's winning of the bid to host the Olympics sparked a construction boom in which city authorities took over property to sell to developers or develop on their own for a profit, compensating residents with below market and non-negotiable sums.

Three generations of the Ye family were evicted from their Beijing home in May 2003, leaving several members homeless because the compensation they were offered was not enough to buy a new home.

Ye Guozhu has been jailed since he and others sought permission in August 2004 for 10,000 people to demonstrate against the forced Olympic evictions.

"They are holding him because of the Olympics, but we don't know whether they'll release him afterwards," his brother said.

Since Ye Guoqiang was released after serving two years in prison for also protesting against the evictions, he has been under 24-hour police surveillance.

"We can put up with being under surveillance, but just let our family be reunited," he said. (dpa)