A further 4,500 British reservists are to be called up ahead of a possible war with Iraq, Defence Secretary Geoff Hoon has said.

The news, in a written Commons statement, triples the number of reservists announced previously, meaning a total of 6,000 are being called up by the UK.

Britain is ultimately expected to have a military presence totalling around 30,000 personnel in the Gulf.

The call-up was announced as UK Prime Minister Tony Blair was due to travel to Spain to complete a week of intense diplomatic activity ahead of crucial talks on the Iraq crisis with US President George W Bush.

ARTICLE SIGNATORIES

Tony Blair, UK Silvio Berlusconi, Italy Jose Manuel Barroso, Portugal Peter Medgyessy, Hungary Leszek Miller, Poland Anders Fogh Rasmussen, Denmark Vaclav Havel, Czech Republic

Mr Blair is among a group of European leaders who have united to back the US stance on Iraq.

The premiers, who also include the leaders of Spain, Denmark and Italy, wrote in a joint article in The Times: "Our strength lies in unity."

Mr Blair's meeting with the Spanish Prime Minister, Jose Maria Aznar, in Madrid on Thursday, follows telephone discussions with the leaders of France, Italy, Canada, Australia, Turkey and Greece.

He will later fly to the US for a meeting with Mr Bush at Camp David.

Restraint?

In Washington, the leader of the Democrats in the Senate, Tom Daschle, said he hopes Britain's prime minister will act as a restraining influence on the US president at Friday's meeting.

Earlier, eight European leaders urged all of Europe to stand united behind America in its tough stance on Iraq.

Notable exceptions were France and Germany, both members of the UN Security Council, which may be asked to vote on launching an attack on Iraq.

Downing Street said later that France and Germany had not been asked to sign the statement.

The BBC has learned that Mr Blair does not think France or Germany should be able to speak for the whole of Europe.

A source told the BBC that the Dutch were also invited to sign the letter to the Times, but declined because they are trying to form a coalition government in the wake of elections.

Among the signatories, only the UK and Spain are also Security Council members.

In the article, which was also published in the Wall Street Journal, the leaders of the UK, Spain, Italy, Portugal, Hungary, Poland, Czech Republic and Denmark say the attacks of 11 September on America "were an attack on us all".

Credibility

They go on to say this week's UN weapons inspectors' reports have confirmed Iraq's practice of "deception, denial and non-compliance".

"We must remain united in insisting that his regime is disarmed," say the leaders.

Blair wants to keep up the pressure as inspections continue

Click here for Andrew Marr on Blair's gamble

The leaders argued the UN's credibility and world stability will suffer if a dictator is allow systematically to violate UN resolutions.

US Defense Secretary Mr Rumsfeld last week dismissed France and Germany as "old Europe" and said the vast majority of EU leaders were "with the United States on this".

Al-Qaeda

On Wednesday evening, Mr Blair met Italian premier Silvio Berlusconi in Downing Street, adding to his series of phone talks with world leaders this week.

In a phone call on Tuesday, French President Jacques Chirac told Mr Blair nothing justified war at the moment, according to a French spokeswoman.

Downing Street upped its persuasion campaign on Wednesday when it said there was evidence al-Qaeda "operatives" were being sheltered in Iraq.

Mr Blair's official spokesman for the first time explicitly linked al-Qaeda and the Iraqi regime, which flatly denied the claim.

Downing Street pointed to links between Iraq and al-Qaeda

Iraqi Deputy Prime Minister Tariq Aziz, speaking on the American ABC television network, challenged the US to produce any evidence of its claims of al-Qaeda links.

Iraq insists it is co-operating with United Nations weapons inspectors.

Mr Blair said that after Iraq had been "dealt with", North Korea would have to be confronted through the UN.

News that an increased number of reservists was being called up prompted Liberal Democrat defence spokesman, Paul Keetch, to express concern.

"The need for reservists underlines the extent of overstretch in the regular forces," he said.