Yemeni authorities have detained several US and French students of Arabic on security grounds, a government official said.
An Australian woman is also reportedly being held for links to militancy.
The government official said the Westerners had been detained in Sanaa at the behest of their own governments, but declined to give details of their arrest.
A source close to the Yemeni government said those held included two Americans and a French citizen, but the government official could not confirm that.
Officials reached at the US and French embassies in Sanaa had no immediate comment.
Yemen, neighbour to top oil exporter Saudi Arabia, has been a key Western security concern since a Yemen-based regional al-Qaeda arm claimed responsibility for a failed December attempt to bomb a US-bound passenger plane.
Yemen's Western allies and Saudi Arabia fear al-Qaeda is trying to exploit instability in Yemen to use the country, with conflicts in its north and south, as a base to launch attacks in the region and beyond.
News of the arrests of the foreign students came days after an Australian woman who had converted to Islam and moved to Yemen was reported detained in Sanaa on what her lawyer said was suspicion of links to unnamed radical Islamist groups.
The lawyer, Abdel Rahman Barman, identified his client as Shyloh Giddens, and said she was arrested because of her ties to a Bangladeshi woman taken into custody in May over suspicion of links to radical Islamists.
Australia's Department of Foreign Affairs and Trade, without naming the woman, said she was detained on 16 May after spending two days under house arrest with her children, aged 5 and 7.
