Sweden has expelled a diplomat from an undisclosed country and a Swedish diplomat has been kicked out in a tit-for-tat move, the foreign ministry said on Monday.

Media reports said the diplomat was from the Chinese embassy which was allegedly involved in spying on members of the Muslim Uighur ethnic group in the Scandinavian country, though the foreign ministry would not confirm that information.

"I can confirm that a diplomat was expelled from Sweden last week. I can't confirm his nationality," a Swedish foreign ministry spokesman, Anders Jörle, told AFP.

Jörle said a Swedish diplomat had subsequently been expelled in response to the Swedish move.

News agency TT said the expulsion was linked to the arrest of a Swedish citizen in Stockholm on June 4 accused of spying on refugees for the Chinese embassy.

"I can neither confirm nor deny that," Jörle said.

Intelligence agency Säpo said on June 4 it had arrested a Swede accused of gathering information on refugees for overseas government consumption after a lengthy investigation and surveillance period.

Säpo would not disclose any information about the man arrested, the foreign country involved, nor any other details of the case.

But TT said on Monday, without citing its sources, that the man arrested by Säpo was a 61-year-old Uighur who came to Sweden as a political refugee in the 1990s and who spied on the 100-strong Uighur community for the Chinese embassy. If convicted, the man faces up to four years in prison.

Most ethnic Uighurs live in China's Xinjiang autonomous region. China regularly condemns militant Uighur nationalists as "terrorists" and accuses the East Turkestan Islamic Movement (ETIM) of carrying out attacks.

The latest US State Department human rights report accuses China of having stepped up repression of the Uighur community.