Saying fighting terrorism should be a prime minister's ''first priority'', Brown also backed police demands to allow intercept evidence to be used in court to help secure convictions against terrorists.
Both measures could form part of the government's legislative slate for the next session of parliament, to be unveiled on Wednesday by Queen Elizabeth.
Britain's top police officer Ian Blair on Saturday called for the 28-day maximum period for questioning suspects to be extended and for the government to lift a ban on phone tap evidence being used in court.
''I completely agree with him (Ian Blair),'' Brown said in an interview in The Sunday Times.
''Given the scale of the threat we face, we must give the security service and the police not just the resources they need, but the powers they need to gather securely the evidence and use that evidence to gain convictions,'' he added.
Brown is the frontrunner to succeed the prime minister who has said he will step down in 2007 and who is widely expected to go in the first half of the year.
Home Secretary John Reid is the only potential challenger who stands a chance of beating Brown who has yet to rule himself out of the race.
Reid, writing in The Sunday Telegraph, fuelled speculation he may still run for the premiership as he attacked opposition Conservative Party leader David Cameron's policies on crime and security.
''The dividing line between David Cameron and I now seems clear,'' he wrote.
The comments from Reid and Brown follow a grim warning on the threat Britain faces from terrorism from the head of the country's domestic spy agency.
Eliza Manningham-Buller, head of intelligence agency MI5, said on Thursday Muslim extremists are plotting at least 30 major terrorist attacks in Britain that may involve chemical and nuclear devices.
Brown said Britain needed a ''national security strategy'' to be updated each year and a national security budget so that funds for fighting terrorism could be accessed easily.
But he dismissed calls from Cameron to create a ministerial post specifically for fighting terrorism.
''It is the prime minister who must take the lead, as Tony Blair has done,'' Brown said. ''If you are prime minister, you cannot devolve responsibility for protecting the nation. It must be your first priority.'' Government plans to hold terrorist suspects for up to 90 days without trial were defeated by parliament but the government is expected to seek to convince legislators to back an extension.
REUTERS AKJ PM1522