LONDON - The World Association of Newspapers and News Publishers (WAN-IFRA) and the World Editors Forum have demanded immediate inquiries into a spate of violent crimes against journalists in recent weeks, including the death of Bulgarian journalist Viktoria Marinova and the alleged murder of Saudi Arabian journalist Jamal Khashoggi.

Calling for a thorough investigation to undermine a culture of impunity in attacks on media personnel worldwide, the organisation also condemned the slaying of Mexican journalist Mario Leonel Gómez Sánchez, and Somali journalist Abdirisak Said Osman.

Ms Marinova was a TV journalist who recently reported on an investigation into corruption involving EU funds. She was reportedly raped before her murder.

Bulgarian officials condemned the attack on Ms Marinova, but they were also insistent that there was nothing to suggest that she had been killed because of her work, reported The New York Times.

They said there was no evidence that she had been threatened, and noted that her car keys, her cellphone and parts of her clothing were missing.

"It is about rape and murder," Interior Minister Mladen Marinov said, a viewpoint that was shared by Prime Minister Boiko Borisov.

The first episode of Marinova's programme aired on Sept 30 and featured two investigative journalists - Mr Dimitar Stoyanov from the Bivol.bg website and Mr Attila Biro from the Romanian Rise Project - discussing their investigation into allegations of fraud involving EU funds linked to prominent businessmen and politicians in Bulgaria.

Bivol.bg owner Asen Yordanov confirmed to AFP that his website had received credible information that its journalists were in danger of being assaulted because of their investigation.

Although there was some disagreement about the extent of Ms Marinova's role in investigating corruption, the questions surrounding her death reflected the tense atmosphere for journalists in the region:

Two reporters in the European Union - Mr Jan Kuciak in Slovakia and Ms Daphne Caruana Galizia in Malta - have been killed in the past year because of the work they were doing to expose graft at the highest levels of government.

"The murder of Ms Marinova is a horrendous and unprecedented crime within the EU, and, if confirmed to have been carried out in retaliation for her work, adds to the growing impression that the enemies of journalism now feel they can kill with impunity," WAN-IFRA said in a statement.

"Following the deaths of Maltese journalist, Daphne Caruana, and Slovakian journalist, Jan Kuciak, Europe must react strongly to end this cycle of violence and provide greater protections for its journalists."

In a separate incident, dissident Saudi journalist Jamal Khashoggi went missing after visiting the Saudi embassy in Turkey. A Turkish official has said the Washington Post columnist was killed inside the kingdom's consulate in Istanbul.

Mr Khashoggi, who had been living in self-imposed exile for the past year, disappeared on Oct 2 after entering the consulate to obtain a document. His fiancee and friends initially said they feared he had been detained or kidnapped for his criticism of the Saudi government.

Speaking to Bloomberg earlier on Sunday, a Turkish government official said Mr Khashoggi was believed to have been killed inside the building. The official asked not to be identified because of the sensitivity of the issue. A Saudi official denied the claim.

WAN-IFRA said it was deeply concerned by the disappearance of Mr Khashoggi.

"We are bitterly aware of the irony of calling upon the world's worst jailer of journalists to act in the interests of press freedom, but if the allegations are even remotely true, then this is a grave act of state-sponsored violence against a journalist that cannot go unanswered," said a statement by WAN-IFRA.

The organisation also called for a thorough inquiry into the slayings of Mr Sanchez, a reporter with local newspaper El Heraldo de Chiapas who was shot and killed on Sept 21 in the town of Yajalón, as well as Mr Osman, a reporter and photographer with the privately owned radio station Codka Nabada, who died on Sept 19 from injuries sustained in an attack the previous day in Puntland, a semi-autonomous area of Somalia.