Britain's policy towards Iran and Syria has not softened, Downing Street says, despite the prime minister's call for them to help bring stability to Iraq.
Tony Blair said the US relationship was crucial
In a major foreign policy speech in London on Monday, Tony Blair said a "whole Middle East" policy includes co-operation with the two states.
But his spokesman insisted that did not mean offering new concessions to the governments in Tehran and Damascus.
Mr Blair also said that alliances with the US and EU are "crucial".
His speech at the Lord Mayor's Banquet outlined British policy in Iraq, the UK's relationship with the US and its position in Europe.
Mr Blair said sectarian violence in Iraq was pushing the country away from its democratically-elected government towards extremism.
While there was help from the UK in rebuilding Iraq, including plugging any gaps in its armed forces, there were also "forces outside Iraq...trying to create mayhem inside Iraq" which needed to be pinned back.
"A major part of the answer to Iraq lies not in Iraq itself but outside it, in the whole of the region where the same forces are at work, where the roots of ...global terrorism are to be found, where the extremism flourishes."
'Obstacles to peace'
Mr Blair went on to say: "There is a fundamental misunderstanding that this is about changing policy on Syria and Iran."
His speech said that it is necessary to start with "Israel/Palestine" as it is "the core" but that progress is also needed in Lebanon, Iraq, and Iran.
Iran is not only refusing to suspend its nuclear enrichment programme, as demanded by the United Nations, but is also "using pressure points in the region to thwart us", he said.
Mr Blair said Iran - by helping the "most extreme elements of Hamas in Palestine; Hezbollah in the Lebanon; Shia militia in Iraq" - were putting "obstacles in the path to peace".
The only way to defeat such barriers was to "relieve these pressure points one by one" and offer Iran the choice of abiding by their international obligations or face isolation, Mr Blair said.
Regarding global alliances, Mr Blair said it is right to keep "our partnership with America strong" and Britain should "rejoice" in its leading role in Europe.
As the world changes, particularly the emergence of China and India, "collective strength" would be needed.
"For that reason, our partnership with America and our membership of the EU are precisely suited to Britain.
"For that reason, it would be insane - yes, I would put it as strongly as that - for us to give up either relationship," Mr Blair said.
Syria's Ambassador to the US, Imad Moustapha, told BBC Radio 4's World at One that his country was willing to engage.
Price of peace
"In one way or another, Syria wants to become a part of the solution to the problem. We are willing to engage and we can help - I'm not claiming we have the magical wand - we can help play a constructive role," he said.
"We have played a constructive role in the past. Syria has invited Israel time and again to re-engage in a peace process."
He added that, for such assistance, "the price should be very clear - we want a comprehensive, fair and honourable Middle East settlement".
The White House's Iraq Study Group is due to give its recommendations on US strategy in Iraq by the end of the year.
After meeting the group on Monday, US President George W Bush said he rejected dealing with Iran unless it suspends its uranium enrichment activities.
"Our focus of this administration is to convince the Iranians to give up their nuclear weapons ambitions. And that focus is based upon our desire for there to be peace in the Middle East... an Iran with a nuclear weapon would be a destabilising influence," Mr Bush said.
President Bush has previously described the countries as part of an "Axis of Evil".
Mr Blair is due to talk to the group on Tuesday.