The High Court has blocked a legal challenge over accusations that the UK Government is unlawfully assisting US drone attacks by passing on information to the CIA.

The son of a Pakistani man killed by a missile from a drone in the north west tribal area of the country wanted permission to apply for a declaration that the provision of assistance by UK intelligence could be "encouraging or assisting murder".

Lawyers for Noor Khan, 27, say intelligence officials could also be committing war crimes by helping to locate targets for drones.

Refusing Mr Khan permission to bring the challenge, Lord Justice Moses said: "The real aim is to persuade this court to make a public pronouncement designed to condemn the activities of the United States in North Waziristan, as a step in persuading them to halt such activity."

The judge said Martin Chamberlain, who appeared for Mr Khan, "knows he could not obtain permission overtly for such a purpose".

He added: "His stimulating arguments have been an attempt to shroud that purpose in a more acceptable veil."

The ruling by Lord Justice Moses, sitting in London with Mr Justice Simon, was a legal victory for Foreign Secretary William Hague, whose lawyers submitted the Khan application for judicial review was unarguable.

Mr Khan lives in Miranshah, North Waziristan Agency (NWA), in the Federally Administered Tribal Areas, and launched his application with the assistance of legal aid.

Mr Chamberlain told the court at a two-day hearing in October that Mr Khan's father, Malik Daud Khan, was among 40-50 victims killed in March last year in a drone strike on a jirga, or council of elders, held outdoors at Datta Khel (NWA). Many others were seriously injured.

During the hearing Lord Justice Moses referred to a "very moving passage" in Mr Khan's evidence of what life was like living with the threat of missiles "falling from the sky without warning".

Mr Chamberlain said a Sunday Times article in July 2010 reported that British spy agencies were pinpointing the hiding places of al Qaida and Taliban chiefs for controversial "targeted killings" by drones.

It also reported that GCHQ, the UK's top secret communications agency, was using telephone intercepts to provide the Americans with "locational intelligence" on leading militants in Afghanistan and Pakistan.

Insiders were quoted as saying GCHQ could provide more extensive and precise technical coverage in the region than its American sister, the National Security Agency, because Britain has a better network of intercept stations in Asia.

The "insiders" were quoted then as saying the Cheltenham-based centre was proud of the work it did with America and it was "in strict accordance with the law", said Mr Chamberlain.

The Foreign Secretary was now "back-tracking" and adopting a "neither confirm nor deny" policy over what was going on, said Mr Chamberlain.

He submitted that Mr Khan was entitled to a declaration that any UK intelligence officers who passed on information to the Americans might be "encouraging or assisting murder", contrary to the Serious Crime Act 2007.

He said they were UK nationals and could be criminally liable under English domestic law, or their actions might constitute war crimes or crimes against humanity.

Mr Chamberlain said: "We say the offence of murder is triable in England where the defendant is a subject of Her Majesty, even where the killing takes place abroad."

In his ruling, the judge said Mr Khan had described his local community as "plagued with fear" as drones hovered over their skies day and night.

Children dared not attend school and people were fearful of gathering together in case they roused suspicion and there were further "brutal assassinations" by drones.

The Foreign Secretary had "neither confirmed nor denied" that the GCHQ was providing intelligence to locate targets.

The judge said Mr Khan contended there was no armed conflict in Pakistan, as recognised under international law, and thus GCHQ employees were not entitled to the defence of "combatant immunity" to avoid prosecution under UK law.

Dismissing the case, the judge said: "I can see no point in identifying whether the employees have a defence to a criminal charge in circumstances where there is no risk they will ever be prosecuted and where the existence of facts likely to found a criminal charge is a matter of imaginative conjecture."

The judge added GCHQ activities were subject to the scrutiny of the Intelligence and Security Committee and the Intelligence Services and Interception Commissioners, whose remit was to hold the Security Services and those responsible for intelligence accountable.

He ruled: "There is no basis on which this court could or should conclude that a declaration would fill a void and impose the rule of law on a lawless territory.

"An abstract declaration would be far less effective than the oversight of the Parliamentary Committee charged with ensuring, amongst other things, that legality does not give way to expediency."

If Mr Khan's application went ahead, there would be the clear impression that it was the United States' conduct in North Waziristan that was also on trial, and any declaration would be "damaging to the public interest without any countervailing justification or advantage".

Later Mr Khan's lawyers said he intended to appeal.

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.

"This claim raises very serious questions and issues about the UK's involvement in the CIA drone attacks in Pakistan."