LONDON (AFP) - Two British nationals, a man and a woman, have been detained in Afghanistan, officials in London said Thursday, reportedly as part of a counter-terrorism operation to stop a possible attack back home. The pair were detained by British and Afghan forces last week and are being held in a secure facility at Kandahar, southern Afghanistan, the Ministry of Defence said. It refused to give any details, or confirm media reports that the pair were arrested in Herat, in the west of the country near the border with Iran, amid fears they were plotting a potential attack on British soil. "We can confirm that two British passport-holders were detained in an ISAF (International Security Assistance Force) operation conducted jointly last week by UK forces with Afghans in support," the MoD said in a statement. "The individuals, a male and a female, are currently being held in a secure facility in Kandahar for questioning."