BBC journalist Shaimaa Khalil released in Cairo Published duration 2 August 2011

media caption Shaimaa Khalil's colleague Jon Leyne explains the circumstances of her release

The BBC journalist Shaimaa Khalil has been released after being detained while reporting in Tahrir Square in the Egyptian capital, Cairo.

The circumstances of her detention on Monday remain unclear, but it came after soldiers, backed by riot police, moved to clear a three-week sit-in.

She was held for 20 hours at a military base, and then taken to the military prosecutor's office before being freed.

It is not yet clear whether she faces further action by the authorities.

Witnesses in Tahrir Square - the focal point of the pro-democracy protests which forced President Hosni Mubarak to step down in February - said activists were beaten and had their phones broken. Anyone taking photographs was targeted, they added.

The BBC's Jon Leyne in Cairo says Ms Khalil was arrested along with about 80 other people, including journalists.

The military authorities, in power since Mr Mubarak left office, have been criticised for the harassment of journalists, but until Monday had not arrested an accredited foreign reporter.

Earlier, the BBC called on the authorities to release Ms Khalil immediately, saying it was "very concerned" about her detention.