The European parliament has jointly awarded a major journalism prize to a consortium of 17 media outlets including the Guardian for the Pegasus spyware scandal revelations.

A series of stories over the summer revealed evidence that global clients of the Israeli surveillance company NSO Group had identified human rights activists, journalists, lawyers and leading political figures, including the French president, Emmanuel Macron, as potential targets for phone-hacking software.

The group of 17 media organisations, led by Paris-based non-profit journalism group Forbidden Stories, picked up the inaugural Daphne Caruana Galizia prize for journalism of €20,000 (£17,000) on the advice of an independent jury of members of the press and civil society from the 27 EU member states and representatives of the main European associations of journalism.

Caruana Galizia was one of Malta’s most prominent and dogged investigative journalists. She was assassinated in a car bombing close to her home on 16 October 2017.

David Sassoli, the president of the European parliament, said: “Daphne Caruana Galizia’s death has brought about a resurgence of investigative journalism by colleagues committed to continuing her work. Recent examples, such as the Pandora papers, have demonstrated the unique power of journalism that is daring and adamant, particularly when carried out in the context of an international consortium.

“By creating transparency, investigative journalism allows voters to make informed decisions. Protecting and supporting journalists is in the vital interest of democratic societies.”

The Pegasus project investigation, which received technical support from Amnesty International, found that the phone numbers of individuals across 50 countries appeared on a database believed to contain targets for potential surveillance.

The investigation was based on forensic analysis of phones and analysis of a leaked database of 50,000 numbers, including numbers for Macron and the European Council president, Charles Michel, along with other heads of state and senior government, diplomatic and military officials in 34 countries.

Last month Hungary’s data protection authority said it had launched an official investigation into allegations concerning the Hungarian government’s use of the Pegasus software.

At least five Hungarian journalists appeared on a leaked list reviewed by the Pegasus project consortium. Also on the list was the number of the opposition politician György Gémesi, who is the mayor of the town of Gödöllő and the head of a nationwide association of mayors.

“An unprecedented leak of more than 50,000 phone numbers selected for surveillance by the customers of the Israeli company NSO Group shows how this technology has been systematically abused for years,” the EU parliament said in a statement.

NSO is an Israeli surveillance company regulated by the country’s ministry of defence, which approves the sale of its spyware technology to government clients around the world.

The company says it sells only to military, law enforcement and intelligence agencies in 40 unnamed countries for the purpose of terrorism and crime investigations. It further claims to rigorously vet its customers’ human rights records before allowing them to use its spy tools.

NSO says it “does not operate the systems that it sells to vetted government customers, and does not have access to the data of its customers’ targets.”

Eve Geddie, the director of Amnesty International’s European institutions office, said: “It is vital that EU countries address these abuses, protect journalists and rights defenders, and ensure robust and meaningful regulation over the cybersurveillance industry both at home and abroad.”