The threat to the UK from al-Qaeda is likely to have increased and the Iraq war has provided a boost to extremist groups, a committee of MPs has found.
It will become harder to tackle the terror threat, says the MPs
The terror network posed "an extremely serious and brutal threat" to the UK, the latest Foreign Affairs Committee report into the "war on terror" found.
Tackling this threat would become more difficult in the future, it concluded.
One reason was propaganda coming from Iraq which is a crucial training ground for international terrorists, it said.
Committee chairman Mike Gapes said al-Qaeda had now broken up into smaller groups which were harder to trace.
"We feel that there is a problem that, although there's been some successes, al-Qaeda as a concept is actually more of a threat now than it was before."
The report also argued that too little effort was being put into communicating with the Arab and Islamic world to counter terrorist propaganda.
It said the continued existence of Guantanamo Bay detention centre diminished US moral authority and added to the list of grievances.
The committee also expresses concerns over the deteriorating security situation in Afghanistan and the arrival there of violent tactics pioneered by militants in Iraq.
The MPs called on the government to clarify the objectives for the British troops who were recently deployed in Afghanistan.
In its response to the report, the government should set out the circumstances under which it would withdraw UK troops from Iraq, the committee recommended.
Former government intelligence analyst, Crispin Black, told the BBC more work needed to be done to reach people who may be persuaded by extremist views.
"What we need to do is to try and communicate directly to the kind of people who might be influenced at some point by the Al Qaeda world picture a sense of our strong good faith, and our sense of really wanting a peaceful and democratic Middle East for everybody," he said.
Fabian Hamilton MP, who sits on the Foreign Affairs Committee, said the war on terror in Iraq was fuelling extremist groups.
He said: "It increases that sense that those terror groups have, that this is a war against Islam by the West, something not shared by pretty well every member of the Islamic faith in Great Britain and most of Europe.
"But that's the way they feel, that's the proposal they put forward and of course Iraq just makes that worse".
The Foreign Affairs Committee called the "continuing deterioration of the security situation" in Iraq and its deepening sectarian and ethnic conflicts "extremely worrying".
It called on the government to respond to other issues in the report, including the level of detentions by coalition forces.
Iran was also a subject of the report, with the committee expressing concern "about the Iranian involvement in Iraq and that the organisation, weaponry and technology for a number of terrorist incidents in Iraq have come from within Iran".
The MPs said that Iran's position towards the war against terrorism had "been contradictory, and extremely unhelpful in a number of key areas".
There was also "clear cause for concern" over Iranian nuclear intentions, the MPs said.
However, the committee commended the co-operation between the UK, France and Germany in their negotiations with Iran.
The MPs said: "Military action would be likely to unleash a host of extremely serious consequences both in the Middle East and elsewhere, and would not be guaranteed to prevent Iran from developing nuclear weapons in the long term."
The government should not undertake or support military action against Iran "until all other options have been exhausted or without broad agreement" among its international allies," the committee said.
"Government should also make these points absolutely clear to the administration in Washington," the MPs added.