The High Court has rejected an attempt by a Pakistani man to force the UK government to reveal if it is providing intelligence for US drone strikes.
Noor Khan, whose father died in a drone strike in Pakistan, said the UK could be committing a war crime by helping the CIA to identify targets.
The government neither confirms nor denies any role in assisting with operations against al-Qaeda.
The court said it could not force the government to reveal its policy.
Lord Justice Moses said that oversight of intelligence arrangements in this case was for Parliament, not the court.
The UK operates its own unmanned drones in Afghanistan, but these operations were not part of this case.
The High Court challenge concerned whether the UK was also helping the US missions against targets in Pakistan's tribal areas.
Mr Khan is to appeal against Friday's ruling.
Conservative MP Rehman Chishti said he was "very disappointed" about the decision taken at the High Court.
He told the BBC: "I think it would have been important to have a full hearing in the High Court which would have clarified if the United Kingdom government provides locational intelligence to the United States which is then used for drones in Pakistan which have then killed over a thousand civilian people."
Mr Chishti, who was born in Pakistan and used to be an adviser to the country's former prime minister, Benazir Bhutto, said he had repeatedly raised the question in Parliament but was not given an answer. He said it was important to gain clarity because it affected national security.
"By creating an anti-West feeling in Pakistan, with over a thousand people dead, I think we have to do everything we can to make it clear whether we provide intelligence or not so that people in Pakistan can determine that we, the United Kingdom, are a friend of Pakistan and not against Pakistan," he said.
Mr Khan's father was one of 50 people killed last year when a US drone bombed a meeting near the border with Afghanistan.
'Living in fear'
The survivors and families said it was a council of elders convened to settle a local commercial dispute, not a gathering of al-Qaeda chiefs.
In his High Court action, Mr Khan's lawyers argued that the UK's secret communications centre, GCHQ, could be providing "locational intelligence" to the CIA which helps it to identify targets for drone strikes.
The lawyers did not ask the court to rule if the US strikes were lawful. But they said British officials could be secondary parties to murder or guilty of war crimes if they were providing critical information to the US.
Mr Khan's community was living in a constant state of fear, the court heard, because they could regularly hear drones passing over head and they did not know if they ere about to be attacked again.
Lawyers for the government argued that the High Court could not make any ruling on the case because sensitive information about the intelligence relationship between the allies could not be made public.
Earlier this year, President Barack Obama confirmed the existence of the drone strike operations over Pakistan and said they were essential in the fight against al-Qaeda.
In a statement after the court ruling, Mr Khan's representative Rosa Curling, from law firm Leigh Day, said: "We are disappointed that the court has decided not to engage in this very important issue, leaving our client no option but to appeal the decision."