The police National Cyber Crime Unit has been asked to investigate claims that computers and mobile phones used by exiled Bahraini pro-democracy activists living in the UK are under illegal surveillance.

A complaint about Bahraini officials’ alleged monitoring of the devices was compiled by the civil liberties group Privacy International (PI) and submitted to the Metropolitan police on Monday.

The remote interference is said to have started after Dr Saeed Shehabi, Jaafar al-Hasabi and Mohammed Moosa Abd-Ali Ali inadvertently downloaded malicious software or had their machines infected by the programs. The intrusive technology is able to copy and transmit documents, remotely turn on cameras and microphones to record, as well as send emails from other people’s accounts, according to PI.

It said the technology involved was FinFisher, software once owned by Gamma International, a company that used to be based in Andover, Hampshire, but is now run by a firm based in Germany.

The complaint is partially based on evidence published in August by Bahrain Watch and WikiLeaks, which, it is said, details exchanges between Bahraini officials and Finfisher staff who were providing technical support.

The three men allegedly targeted are human rights activists who oppose the current regime in Bahrain and have been granted asylum in the UK.

Moosa Abd-Ali Ali and Hasabi had both been detained and tortured in Bahrain. Shehabi has been sentenced to life imprisonment in absentia and had his Bahraini citizenship revoked.

“We often had the feeling that they were spying on us but we had no physical evidence of intrusion,” said Shehabi, 60, who is a journalist. “I have lived here since 1971. I thought I was under British protection.”

His only direct evidence of computer interference was when his Twitter account inexplicably began following more and more people; on another occasion, he said, his daughter’s travel plans were disclosed to Bahraini government officials. Three years ago his home in the UK was the target of an arson attack.

Hasabi, 43, an IT specialist, said he had received numerous emails which he did not open because they appeared suspicious. He was alarmed to see his computer’s details appear in the WikiLeaks list online.

Moosa Abd-Ali Ali, 33, a TV camera operator, said: “Many times I received notices from my friends that I had sent them emails when I had not. Once I opened up my Facebook page and found that someone was writing it. Later I found it had been deleted. On other occasions I received notices from Gmail saying someone had tried to hack into my account.

“When I first came to the UK I felt safe but I don’t any more. They have hacked my computer.”

PI said: “It is clear from the Gamma documents published online that among those targeted by the Bahraini government with FinFisher technology were Mohammed, Jaafar and Saeed, along with prominent Bahraini opposition politicians, democracy activists and human rights lawyers.

“FinFisher was developed and produced by the British company Gamma International. Promotional material for FinFisher shows that it allows its user full access to a target’s infected device and everything contained within it, even enabling them to turn on functions such as cameras and microphones.

“Reports from the Citizen Lab suggest that FinFisher command and control servers have been found in 35 countries, including Ethiopia, Turkmenistan, Bahrain, and Malaysia.”

The National Cyber Crime Unit is part of the National Crime Agency. Earlier this year PI made a similar complaint to police about alleged surveillance of the computer of an Ethiopian activist living in the UK.

Commenting on the alleged surveillance of the Ethiopian, a Metropolitan police spokesperson said: “On 28 February 2014, we received an allegation that a man in Islington had had his computer accessed without authorisation. This matter is currently under investigation by Islington CID.”

PI alleges that surveillance carried out by Bahraini authorities amounts to unlawful interception of communications under section 1 of the UK’s Regulation of Investigatory Powers Act (Ripa) 2000.

FinFisher and its previous owner Gamma have previously claimed they only sold their products to responsible governments. The German-based firm did not respond to requests for a comment, nor did the embassy of Bahrain.