David Cameron is facing questions over the decision to carry out a drone strike in Syria which killed two British Islamic State jihadists.
Cardiff-born Reyaad Khan, 21, and Ruhul Amin, from Aberdeen, died last month in Raqqa in the first targeted UK drone attack on a British citizen.
The PM said the “act of self defence” was lawful, despite MPs previously ruling out UK military action in Syria.
Labour is calling for ministers to publish the legal basis for the attack.
In a Commons statement on Monday Cameron said both Khan and Hussain had been involved in actively recruiting IS “sympathisers” and were plotting to attack “high-profile public commemorations” taking place in the UK this summer.
Khan was killed in a precision strike on August 21 by a remotely piloted aircraft, “after meticulous planning”, while he was travelling in a vehicle, MPs were told.
Another British national, Junaid Hussain, 21 and from Birmingham, was killed in a separate air strike by US forces in Raqqa on August 24, reports the BBC.
Cameron said the attorney general had been consulted and agreed there was a “clear legal basis” for the strike on Khan.
But questions have been raised over the decision with acting Labour leader Harriet Harman urging the government to publish the legal advice.
She called for “independent scrutiny” of the attack, asking: “Why didn’t the attorney general authorise this specific action rather than merely ‘confirming there was a legal basis for it’?”
Former attorney general Dominic Grieve said it was possible the decision taken by the government could be “legally reviewed or challenged”.
Labour leadership candidate Jeremy Corbyn said “urgent consideration needs to be given to the appropriate process by which attacks such as this one are sanctioned, on what evidence and on what basis of law”.
David Davis, former shadow home secretary, said he believed the strike was justified but warned of “the possibility that this translates or becomes routinised into something like the Americans’ position”.
