Unidentified assailants set one of the few churches in Yemen's second city Aden on fire on a day after it had been damaged by vandals, witnesses said.
The masked arsonists torched St Joseph, a Roman Catholic church in the central Crater neighbourhood of the port city, which is controlled by loyalists of the exiled government on Wednesday.
A security official said the attackers could be militants of Al-Qaeda.
"The church is in flames," resident Moetaz al-Maysour told AFP, adding that "masked men started the fire."
Yemen's population is 99% Muslim.
Of the 22 churches that operated in Aden when the city was a British colony before 1967, only a few remain open, used rarely by foreign workers and African refugees.
Al-Qaeda militants have been accused of several attacks since pro-government forces pushed Iran-backed rebels out of the battle-scarred city in July with support from a Saudi-led coalition.
The jihadist network's Yemen branch, regarded by Washington as its deadliest, has exploited the fighting to boost its presence in swathes of the south and east.