BEIJING (AFP) - China has arrested an American Christian aid worker based near its border with North Korea, his lawyer said on Saturday, as the authorities deepen an apparent crackdown on religious groups in the region.

Peter Hahn, a North Korean-born naturalised United States citizen, was formally arrested on Friday on charges of embezzlement and counterfeiting receipts, his attorney Zhang Peihong said.

Many Christian groups, mostly run by South Koreans, are active along the border. But they are forced to operate underground as China bans foreign missionaries and vows to arrest refugees escaping persecution in North Korea.

Hahn has been based in the border city of Tumen since the late 1990s, when he founded a Christian non-governmental organisation providing aid to North Korea and help for refugees. He set up a vocational school for local teenagers in 2002.

A source with direct knowledge of the case but who declined to be named told AFP that several foreign workers associated with Hahn's charity have been deported in recent months.

The authorities this summer froze Hahn's bank accounts and barred him from leaving China, according to Chinese media reports.

The 74-year-old maintains his innocence of the charges, which "cannot be stood up", Mr Zhang added.

Hahn is likely to face trial within three months, he said. The maximum sentence for the two crimes is 12 years in prison.

US state department spokesman Jen Psaki confirmed the arrest at a briefing and said a consular officer visited Hahn in jail on Friday.

It comes months after the Chinese authorities levelled espionage accusations against a Canadian couple also living close to the North Korean border who provided aid to Christians fleeing the country.