British troops are on the frontline at the head of a NATO force in southern Afghanistan, and have suffered increasing casualties in recent months in the face of unexpectedly fierce resistance from Taliban fighters.
Blair, who visited British forces there on Monday, told Britain's lower House of Commons that he would raise the issue of so-called "national caveats" at a NATO summit in Latvia next week.
Conservative opposition leader David Cameron suggested that such restrictions on the use of some countries' troops and equipment in the operation effectively left the NATO force fighting "with one arm tied behind its back".
"We do raise the issue of the caveats the entire time. Several countries, for reasons to do with their own politics, are reluctant to remove them," Blair responded in his weekly question and answer session with lawmakers.
"However, what we will be saying is even if they retain some caveats on the deployment of their forces particularly in a fighting situation that nonetheless there is much more that could be done for example to give support to reconstruction and redevelopment."
Blair put Afghanistan at the heart of the West's "war on terror" Monday and told British troops that their desert battles with the Taliban would decide the future of world security.
At a news conference in Kabul later, he urged NATO members to re-engage with Afghanistan by acknowledging the progress made there since the Taliban were ousted by US-led forces in late 2001.
He repeated the message on Wednesday, saying that the Riga summit was an opportunity "to make sure that not just the United Kingdom but all of NATO are doing their utmost" to bring peace and security to Afghanistan.
He added: "It's important that NATO recognises that the credibility of NATO, not just the security of our world, the prospects for Afghanistan, ... rests on us doing everything that we can to help the people of Afghanistan in their search away from the Taliban and in favour of democracy."
Britain has about 5,500 troops in Afghanistan -- the second-largest contingent in the 37-nation, 31,000-strong International Security and Assistance Force set up to bring stability to the troubled country and aid reconstruction.

Copyright AFP (Agence France-Presse), 2006