NATO has handed over control for security in Afghanistan's western Herat province to Afghan security forces.

Herat is the fourth of seven areas to accept responsibility for its own affairs in the initial phase of the transfer. A ceremony was held Thursday in the provincial capital, Herat, to mark the handover.

Earlier this week, coalition forces turned over control of central Bamiyan province, the capital of eastern Laghman province, Mehterlam, and the capital of southern Helmand province, Lashkar Gah.

NATO is handing over security to Afghanistan's army and police in a gradual process due to be completed by the end of 2014, clearing the way for most foreign troops to return home. Afghan President Hamid Karzai has long pushed for the handover.

Also Thursday, British forces detained two Britons in Afghanistan, amid media reports the two were suspected of fighting for the Taliban.

In London, Britain's foreign office Thursday confirmed the detention of the two British nationals and said embassy staff is providing assistance. No other details were given.

Afghan officials told news agencies that the suspects had links to the Taliban and were recently arrested at a hotel in Herat.

But The Times of London newspaper reported earlier that the suspects were detained in southern Helmand province late Tuesday during an operation by British forces in response to a “suspected threat” to British security.

Britain has about 9,500 troops in Afghanistan as part of the NATO-led force.