A grenade has been unearthed by anti-terror police searching the grounds of an Islamic school - but it is a leftover from the First World War.

Bomb disposal experts were called to the Jameah Islamiyah School in Catts Hill, Mark Cross, near Crowborough to make the rusting explosive safe.

The grenade is being treated as an archaeological find, rather than evidence in the investigation into the school, which is suspected of being a training camp for militants.

A spokesman for Scotland Yard confirmed the find but refused to say whether any other weapons had been discovered. Dubbed Britain's first Jihad training camp, the former ballet school in secluded countryside was said to have played host to terrorist recruitment camps inspired by Al Qaeda.

Dozens of officers swooped on the school on September 1, following months of surveillance by MI5.

The same day, a group of 14 men were arrested as they sat down to eat in a Chinese restaurant in London after returning from a trip to the school.

Five families who were lodging at the school when it was raided have been moved to the four-star Thistle Hotel in Kings Road, Brighton, where rooms start at £110 a night and rise to £360 for a deluxe suite.

The 25 people are not connected to the investigations.

The cost, which is being covered by the Metropolitan Police, is estimated to be just under £10,000 so far.

Some people went to stay with relatives but police arranged rooms at the Thistle for the others.

One man said: "It was either stay here or live on the street."

A police spokesman said: "They will stay as long as the search takes."