The war has just begun, there will be many tough fights ahead

Downing Street document

Ahead of the meeting the prime minister's official spokesman said: "We can't stick our heads in the sand and pretend these things (weapons of mass destruction) don't exist because they do."

"The threat of global terrorism is real. The threat of weapons of mass destruction is real.

"It is important to remember the atrocities of 11 September."

The spokesman stressed no decisions had been taken and the weapons issue was being examined in a "calm, measured way".

10-day mission

Mr Cheney and Mr Blair are discussing the progress of the coalition formed in the wake of the terror attacks on America, exactly six months ago, as well as other issues such as US tariffs on steel imports.

The stop in London comes before Mr Cheney embarks on a 10-day tour of the Middle-East, where he will seek help in the war on terrorism and views on action against Iraq.

Some Labour MPs are pressing Blair not to join action against Iraq

The visit comes as Mr Blair faces growing domestic disquiet over military action against Iraq - many Labour MPs are among the 70 who have signed a motion opposing action.

Meanwhile Richard Pearle, who advises US President Bush on defence, said he was disappointed with the reaction of "a number of America's friends in Europe".

These countries, he told BBC Radio 4's Today programme "pay very close attention to threats to their security, but when the threats are to American security, they are nowhere to be found".

Downing Street has published a document stressing that the war against international terrorism has a long way to run.

Coalition 'steadfast'

The 35-page document also says the war could include military action on targets other than Afghanistan.

It said: "There are many countries where adoption of terrorist methods or the presence of terrorist or extremist networks causes us grave concern.

"We will take action we deem necessary in support of this aim, including military action, if absolutely necessary."

It said the coalition was "working to constrain those groups and regimes believed to be seeking to acquire weapons of mass destruction".

The document said the coalition's objectives remained:

• to do everything possible to eliminate the threat posed by international terrorism
  
• to deter states from supporting, harbouring or acting complicitly with international terrorist groups

The US has threatened to remove Saddam Hussein by force

Labour chairman of the Commons' foreign affairs committee, Donald Anderson, called on the UK government to calm any "reckless" elements in the Pentagon who were "on a roll".

Home Secretary David Blunkett told Today the UK Cabinet had discussed the impact the action would have globally, including in the Middle East.

"There is no point in going to war unless you know what the objective is and that you weighed up what the consequences would be," he said.

But the consequences of taking no action also had to be taken into account, he added.

MPs opposed

International Development Secretary Clare Short, however, said while she would like to see Saddam's regime ended, she would not support "mass attacks on the poor old Iraqi people".

The US has threatened action against Iraq even if it lets UN weapons inspectors - who would establish how many weapons of mass destruction it has accumulated - back into the country.

Liberal Democrat foreign affairs spokesman Menzies Campbell said Mr Blair should make it clear that "military action is not the first option, but should only be considered when all other reasonable options have been excluded".

On Monday, Labour MPs Alice Mahon and Tam Dalyell, the longest serving MP, will deliver a letter to Downing Street warning Mr Blair against joining any action against Iraq.