Egypt on Saturday deported three American students arrested during protests in Cairo's Tahrir Square to demand an end to military rule, an airport official told AFP.

The three students of the American University in Cairo were ordered released on Thursday after three days in custody.

According to the official MENA news agency, the trio had been arrested with a bag allegedly containing a water bottle filled with petrol -- as clashes raged around Tahrir between police and protesters.

Thousands of protesters had since Friday converged on Tahrir -- the epicentre of protests that toppled Hosni Mubarak -- to demand that the ruling military hand power to a civilian authority.

On Thursday, the United States thanked Egypt for expediting the case.

State Department spokesman Mark Toner said US officials were in contact with the students and their families as they provided consular assistance.

"We appreciate the ongoing expeditious consideration of this case by the Egyptian authorities," he said in a statement.