Almost a quarter of a billion pounds of extra security funding will give momentum in the battle against terrorism, Northern Ireland's chief constable said.

Extra detectives, more equipment and ground and air transport will be secured following the agreement between the Treasury and Northern Ireland Executive.

A total of £199.5 million will come from London and £45 million from the Executive's reserves over the next four years.

Chief Constable Matt Baggott said the extra cash gave the Police Service of Northern Ireland the ability to plan long-term strategies against dissident republicans. "This additional money is all about increasing our ability to keep the momentum going, to keep people safe," he said.

The threat level from dissident republicans is severe, with Home Secretary Theresa May among those warning of the danger posed.

Justice Minister David Ford welcomed the extra money. "Justice has a difficult settlement, the same as every other department has but by having this access to the additional funding and having the four-year grant that puts us in a better position," he said.

The chairman of the Northern Ireland Police Federation, which represents rank and file officers, said more officers are needed in addition to the extra funding. Terry Spence has attacked the police's decision to freeze recruitment as part of its wider savings plan. More than 400 officers are due to leave by the end of March under a severance scheme.

But Mr Baggott said more people were being charged with terrorism offences and the pressure would continue with an increased street presence. He appealed for the backing of the community. "This is simply our police, a police service working under European law," he said.

The chairman of the Northern Ireland Affairs Committee at the House of Commons, Laurence Robertson, said he was pleased the extra money had been provided.

"Paramilitary organisations still, unfortunately, pose a threat to the security of people in Northern Ireland, and perhaps in the mainland, so it is essential that we do everything we can to support the brave men and women of the PSNI in their work."