The system of travel advice given by the government to warn of terrorism and other threats is to be overhauled after last year's failures to warn about al-Qaida's bomb risks on Bali and Mombasa.

Extra resources will produce a more "user-friendly" system as part of a Foreign Office review of priorities, its most senior civil servant said yesterday.

Speaking about next week's conference in London which will bring together more than 150 of Britain's ambassadors, Sir Michael Jay, the permanent under secretary, said he believed the Foreign Office needed to modernise its global network of embassies. He did not rule out the possibility of some closures.

A report last month by the Commons intelligence and security committee on the assessment of the level of threat to British interests concluded there had been a "serious misjudgment" in issuing travel advice about Bali.

Before the Bali bombing, which killed almost 200 people, the unit in the Foreign Office responsible for putting out travel advice had a staff of four. It now has six and is to be further reinforced.

"We will be putting more resources into travel advice," Sir Michael said. "I have asked all posts to look at how they put advice out, how they make it user-friendly. It's going to be a more central [activity] as terror becomes more part of our lives.

"It's never going to be easy and sometimes we will get it wrong. If we publish every threat, as the prime minister said, we will discourage everyone from going anywhere."