Enlarging the EU will be at the centre of Britain's foreign policy as will a strong commitment to overseas development.

New foreign secretary Jack Straw told MPs on Friday that widening the EU would be a high priority, along with playing a more coherent role in Nato. Straw signalled that in order to achieve its goals, his department would be working more closely with other parts of Whitehall.

He said that British military intervention in Sierra Leone showed "a clear determination to our commitment to peace and stability". He added that "military intervention is not, and cannot be, the only instrument at our disposal".

His department would be building on its work with Clare Short and the overseas development ministry, building on the work of the last four years.

Straw set out the background to foreign office thinking saying that as a nation we are expanding more per capita than the USA or Japan and are now the world's fourth biggest economy.

"The British people are travelling overseas more and more - 53 million visits last year. That's one visit for every man, woman and child," Straw said.

The foreign secretary said Britain would continue to pursue its policy of engaging with other nations. "Isolationist policies have rarely benefited anyone - especially Britain which has long earned a living from overseas," he said.

"We benefit by belonging to the world's most influential networks. We will continue to meet the challenge of global change," he said.

For the Conservatives, Francis Maude opened with an attack on the former foreign secretary, Robin Cook.

"Britain's standing in the world was not enhanced by his predecessor's conduct," he began.

Maude described the foreign office as "an absolute Rolls Royce" that had to have a strong leader. "Even a Rolls Royce requires a driver," he said.

Straw signalled who he believed the man at the wheel is by waving his driving licence from behind the dispatch box.

The shadow foreign secretary said the UK was not a minor player on the world stage.

"We are not on the edge of anything. Britain is at the centre of a whole series of networks," he said. "We should be more confident about Britain's role as a nation state."

Liberal Democrat foreign affairs spokesman Menzies Campbell attacked American plans for a missile defence system and British air patrols over Iraq.

"I think it is disingenuous to say they [America] haven't asked us so we can't debate it," Campbell said. "We know there is a nuclear cell in the Ministry of Defence. What have they been doing?"

On Iraq, he said that RAF pilots were subject to unacceptably high levels of danger. "The risk is that one of these days the Iraqis will get lucky... It may well be a British crew who are shot down and dragged through the streets. We need a wholesale review on policy towards Iraq."