Students today gagged the giant heads outside Oxford’s Sheldonian Theatre to protest against plans for a new immigration centre near Bicester.

The Oxford University students, who are members of Student Action For Refugees (STAR), carried out the short-lived stunt in Broad Street shortly after midnight before police stepped in and told them to take them off.

They used white bedsheets to gag the emperors’ heads to symbolise the way detainees are “being silenced”.

But it only lasted 10 minutes before the police arrived.

Aisha Mirza, 19, who is studying human sciences at St Catherine’s College, said: “The police asked us to remove the gags, which we did immediately.

“They informed university security, who drove past once they had seen that the gags were removed. No-one was arrested and no names were taken.”

At 1.30pm today the students will gather outside the Sheldonian Theatre and march to Bonn Square, where there will be speeches at a rally.

The students are protesting against Government plans to build the Bullingdon Immigration Removal Centre in Piddington, near Arncott, for 800 detainees.

Miss Mirza added said: “The site near Bicester could soon be housing the biggest detention centre in Europe if plans go ahead.

“This was a publicity stunt to draw attention to the plight of detainees like those at Campsfield House in Kidlington.

“The gags symbolise the way that detainees are not being given a proper opportunity to put their case.

“We had no intention of damaging these historic statues — this was a purely symbolic protest.”

Miss Mirza said about 50 people were expected to attend the rally in Bonn Square.

Cherwell district councillors will decide whether to give planning permission to the Piddington centre at a meeting on March 12.

In 2007, Oxford novelist Roma Tearne blindfolded four of the stone emperor heads outside the Museum of the History of Science, next to the Sheldonian.

There are 13 statues outside the Sheldonian itself, which were erected to mark its front boundary when it was built from 1662 to 1668.

When the Old Ashmolean — now the Museum of the History of Science — was built next door in 1679 to 1683, four matching heads were carved.

The originals lasted two centuries but by the mid-1800s began to crumble.

New heads were put up but students vandalised them, and they began to weather badly because of the harsh cleaning needed.

In the 1970s, sculptor Michael Black, along wth two assistants, carved the new set.