BRITAIN has "offered every support" to Belgium in dealing with the "appalling and savage" terror attacks in Brussels, David Cameron said.

The Prime Minister promised full backing in a phone call with counterpart Charles Michel after chairing a 40-minute meeting of the Government's emergency Cobra committee to discuss the atrocity.

"We absolutely stand with them at this very difficult time," he said.

"These were attacks in Belgium. They could just as well be attacks in Britain or France or Germany or elsewhere in Europe and we need to stand together against these appalling terrorists and make sure they can never win.

"I have made sure that we have offered every support to the Belgian security and policing and intelligence forces at this time."

Britain was doing "everything we can to enhance our own security", with the police presence being reinforced at ports, airports, underground stations and international railway stations.

"These are difficult times, these are appalling terrorists. But we will stand together to do everything we can to stop them and to make sure that although they attack our way of life and attack us because of who we are, we will never let them win."

The overall threat level had not been raised at this stage from "severe", he said, meaning an attack was "highly likely" but Cobra would continue to meet to assess any new threats.

The Prime Minister's official spokeswoman said arrangements were being made to lower flags to half mast on government buildings and to raise the Belgian flag over Downing Street as a mark of respect for the victims.

Cobra met for around 40 minutes, with Home Secretary Theresa May, Foreign Secretary Philip Hammond, Defence Secretary Michael Fallon and Transport Secretary Patrick McLoughlin among the ministers present.

Representatives of the intelligence agenices, Metropolitan Police Commissioner Sir Bernard Hogan-Howe and the National Security Adviser Sir Mark Lyall Grant also took part.

The Prime Minister's official spokeswoman said that the police and intelligence agencies were already in touch with their Belgian counterparts to discuss what additional assistance they could offer.

"There is an increasing number of specialist dog searches and also more security at St Pancras (the Eurostar terminal)," the PM's official spokeswoman said.