The government is under mounting pressure to stop British companies selling surveillance equipment to authoritarian regimes amid fears they are using it to hack the mobile phones and computer systems of political opponents.

Human rights groups believe a loophole in export controls is allowing the technology to be sold to foreign security services under civilian, rather than military, licences.

Concerns have recently been raised about the export of equipment to Saudi Arabia, Honduras and the Philippines, three countries which have been heavily criticised for their attitude to human rights.

In a statement last month, the government said it was tightening rules to make sure such equipment was not exported illegally. The latest strategic export controls data reveals that a request to export surveillance technology to the Philippines was declined earlier this year.

But lawyers acting for the campaign group Global Justice Now (GJN) believe that many other licences have been granted contrary to export laws. “In their desperation to establish Britain as a great post-Brexit power, human rights have come a very poor second to selling whatever we can to whoever we can,” said Nick Dearden, director of GJN. “No regime is too repressive to receive dangerous products which allow them to maintain their hold on power and silence their opponents. This has grave implications for the international controls on these products.”

In a letter to Liam Fox, the international business secretary, GJN claims that between 1 January 2016 and 31 March 2018 export licences were granted “for various items of surveillance equipment and technology to a number of states with a record of internal repression”. It continues: “Many of the states identified have an established record of major violations of international human rights obligations, including the targeting of journalists, trade union activists, bloggers or simply those that do not share the political views of the ruling regime. Such persons are often subject to harassment, imprisonment, torture or, in some cases, extra-judicial assassination by, or at the behest of, public authorities.”

Laws preclude the British government from granting an export licence if there is a clear risk that equipment might be used for internal repression or could result in a serious violation of international humanitarian law. GJN is now considering whether to launch a judicial review to determine whether the government is in breach of these laws for having failed to adequately assess the export applications.

“Surveillance equipment can be just as harmful as bombs and bullets in repressing those that disagree with a certain regime or seek to speak out against human rights abuses,” said Rowan Smith, human rights solicitor at Leigh Day, which is acting for GJN.

A spokesman for the Department for International Business said: “Risks around human rights abuses are a key part of our licensing assessment and the government will not license the export of items where to do so would be inconsistent with any provision of the Consolidated EU and National Arms Export Licensing Criteria.”