The report calls for an analysis of US interrogation techniques
The British government should not rely on US assurances that it does not use torture, a report by MPs says.
The foreign affairs select committee said the UK and US differ on their definitions of what constitutes torture and it urged the UK to check US claims.
It recommended the government carry out an "exhaustive analysis of current US interrogation techniques."
The MPs also said the government should check claims that Britain is not used by the US for "rendition" flights.
The committee highlighted the technique of "water-boarding" - a practice which simulates drowning.
The US describes it as "a legal technique used in a specific set of circumstances" and President Bush has refused to ban it.
However, the UK Foreign Secretary David Miliband said it is torture and "the UK unreservedly condemns the use of torture."
In its report, the committee said: "Given the clear differences in definition, the UK can no longer rely on US assurances that it does not use torture, and we recommend that the government does not rely on such assurances in the future."
The MPs also challenged the government to check more actively that Britain had not been used by the Americans for so called "rendition" flights - when detainees are taken to countries where bans on torture may not apply.
The UK had repeatedly accepted assurances that it had not, but it was discovered earlier this year that two rendition planes refuelled on the British territory of Diego Garcia in the Indian Ocean.
The MPs stressed the UK had a "legal and moral obligation" to ensure no more of these flights landed on British territory.
A change in approach would have implications for the extradition of prisoners to the US, particularly in terror cases, as a United Nations convention bars the return of individuals to states where they are at risk of being tortured.
Human rights groups have protested about water-boarding
The MPs also urged the Foreign Office to investigate allegations that the UK "outsourced" interrogation of six terror suspects to Pakistan's ISI intelligence agency, where they were tortured and interrogated by British intelligence officers.
Foreign Office minister Lord Malloch-Brown told the committee: "We absolutely deny the charge that we have in any way outsourced torture to Inter-Services Intelligence (ISI) as a way of extracting information, either for court use or for use in counter-terrorism."
Human rights campaign group Amnesty International UK said the report justified its call for an investigation into terror techniques and rendition.
The group's head of policy Jeremy Croft said: "While we have always stressed the need to combat terrorism, we share the committee's concerns over the UK government and its current counter-terrorism policy."
He added: "In particular, the UK government needs to take allegations of torture at Guantanamo and other US detention centres altogether more seriously.
"This must mean pressing harder for proper trial or safe release of Binyam Mohamed, Shaker Aamer and Ahmed Belbacha - three Guantanamo prisoners who are either formerly resident in the UK or with links to the UK."
Andrew Tyrie MP, the chairman of the all-party parliamentary group on extraordinary rendition, said the government must demand answers from the US.
"The committee's conclusions amount to saying that we can no longer rely on assurances from a US administration that purports to uphold the civil and political standards of behaviour, while in fact kidnapping people and taking them to places where they may be maltreated.
"Only by practising what we preach will we be able to win back the support of Muslim communities at home and abroad and build the strongest coalition around the world against terrorism."