China has convicted and released a Korean-American Christian aid worker arrested near its border with North Korea after holding him for nine months, his lawyer told AFP Monday.

Peter Hahn, a North Korean-born US citizen, was detained late last year in a Chinese border city where he had founded a Christian charity providing aid to North Korea.

Authorities released Hahn on August 17, after a court sentenced him to nine months in jail for "counterfeiting receipts", his lawyer Zhang Peihong said.

Hahn, in his 70s, is currently recovering from unspecified health problems in the South Korean capital Seoul, Zhang added.

Many Christian groups -- often run by South Koreans -- are active along the sensitive border.

Most operate underground because China bans foreign missionaries and arrests refugees attempting to escape North Korea.

Hahn's arrest came after a Canadian Christian couple who ran a coffee shop in the Chinese border city of Dandong were detained on espionage charges.

That couple, Kevin Garratt and Julia Dawn Garratt, aided North Korean Christians fleeing the country and their detentions sparked an outcry from Canada.

Julia Dawn Garratt was released on bail in February, China said, adding that her husband had been placed under formal criminal detention.

Hahn has been active in the border city of Tumen since the late 1990s. He set up a vocational school for local teenagers in 2002.

Zhang said that in court Hahn "admitted that he used some fake receipts in China to save money, but maintained he was innocent of a crime".

The US embassy in Beijing did not immediately respond to a request for comment.

Chinese authorities often count prison terms as beginning at the time of initial detention, and Zhang said Hahn served a full sentence.

"He can't come back to China at the moment... all his projects are currently suspended," he said.