London's police forces have launched an advertising campaign urging members of the public to be vigilant against the threat of terrorism.

The move, part of the Life Savers campaign by the Metropolitan and City of London police forces, includes a free and confidential hotline for concerned people to call.

Anyone with information should call 0800 789 321.

"All communities have a role to play in tackling the terrorist threat," said head of the Metropolitan Police anti-terrorist branch, deputy assistant commissioner Peter Clarke.

"I would urge anyone - whether they live in London or elsewhere in the UK - who has information about suspicious behaviour to contact us."

City of London commissioner of police James Hart also called on workers in the financial sector to look out for dubious transactions.

"The public's role in the fight against terrorism cannot be underestimated and the City community is no exception," he said.

"As well as remaining alert to suspicious objects or individuals during their daily routines, people who specifically work in the financial sector can also play a significant part by reporting suspicious financial activity.

"Terrorists require money - if we can cut off that supply we can seriously impede their activities."