The head of a Chinese house church organisation and his wife have been released by authorities after more than three weeks of detention.

Since their arrest on August 6, Pastor Bike Zhang Mingxuan and his wife Xie Fenglan had been on a ''forced vacation'' and shuffled between four different locations, Pastor Bike told China Aid Association president Bob Fu after his release last Friday.

During this period, the couple was heavily guarded by 15 to 16 government officials, including high-ranking public security bureau leaders.

Pastor Bike, one of the most outspoken evangelists in China, said even under captivity he actively tried to evangelise and advocate for house churches to his captors.

"CAA is thankful for the release of Zhang and his wife and for the thousands of supporters who took time to sign the petition," Fu wrote in an e-mail update. "While Zhang and his wife have been treated well by Chinese authorities during their detention, the same can not be said of countless other individuals who continue to suffer at the hands of CPC officials who continue to prohibit the growth of true religious freedom within China."

Since the couple's detention, CAA and Voice of the Martyrs have circulated a petition calling for their release. The petition had picked up more than 50,000 signatures by the time the couple was freed.

Fu said Pastor Bike and his wife were both excited and thankful to hear that so many people cared.

Prior to their August 6 arrest, the couple were reportedly harassed and intimidated by government authorities to the point of being forced to live on the streets. Officials repeatedly threatened landowners, hotel managers, and friends and families who gave them shelter, forcing them to voluntarily leave to avoid further disturbance to business owners and friends.

Officials had said that the couple were being expelled from Beijing because "Bike Zhang met the Americans, and destroyed the harmony of the Beijing Olympic Games", according to CAA.

Although the couple have been released, they are still prohibited from returning to Beijing until the end of the Paralympics on September 16.

Texas-based CAA says it plans to print and deliver the 50,000 signature petition to the Chinese Embassy in Washington DC this week.