A Commons committee has warned that restrictions on defence exports could "blunt the effectiveness" of a UK-US treaty.

The Defence Trade Co-operation Treaty between Britain and America was signed earlier this year by former prime minister Tony Blair and US president George Bush.

The treaty is yet to be ratified and MPs in the Commons defence committee said on Tuesday it was important that the regulations "are not drawn too restrictively".

Describing current restrictions as "unduly burdensome and time-consuming", it said that change was needed to the procedures.

"The US and the UK are very close allies, co-operating closely on defence and security," the report said. "Our soldiers are fighting side by side in Iraq and Afghanistan.

"It is vital to the interests of both the US and the UK that the system should not prevent our forces from getting access to the equipment they need to fight effectively alongside their US allies in current and future operations."

Chairman James Arbuthnot said the committee was "fully behind the principle" of the treaty, but warned that there must not be "a long list of exclusions" when it was implemented.

He added: "This is not just in the interest of the UK and the UK defence industry: the US defence industry is also strongly in support of this treaty and it should benefit US troops as well.

"We hope that our colleagues in the US Congress will agree that it is in all our interests to remove the barriers to defence cooperation. We trust that the treaty will be ratified in both countries without delay."