She said the government had changed how it compiled the figures and only included them if police considered the case "work related".

This had resulted in a remarkable discrepancy in the number of killings listed by the police and those compiled by human rights groups.

By narrowing the definition, police say only 43 work-related killings are considered attacks on press freedom" from 2001 to November last year. In contrast, the NGO Centre for Media Freedom and Responsibility says 92 media professionals were "killed in the line of duty" from 2001 to January last year.

Police Superintendent Henry Libay, the chief of the task force that investigates media killings, said only if the person's work, such as a hard-hitting exposé or commentary, was directly linked to the case would it be classified as "work-related".

"We count those that are work-related but it doesn't mean we don't investigate the others," Libay said.

Paraan said police were quick to attribute attacks on media workers to non-work-related issues, such as land disputes, conflicts with neighbours or romantic problems.

She also said the task force looking into media killings excluded from its count the 31 journalists shot dead in the 2009 Maguindanao massacre, in which 58 people were gunned down in election-related violence.

Libay confirmed that his unit excluded the massacre victims because another unit was investigating it. This means they are excluded from the official statistics his unit sends to foreign human rights organisations.

The US State Department previously tied aid to human rights but lifted restrictions in 2010. Its 2013 report, released on Friday, noted that media killings continued in the Philippines.

Libay drew controversy last year by describing the reporters murdered in Maguindanao as "collateral damage" in an "election-related killing".

He later said he did not mean to offend anyone, but had used those phrases during "a classroom discussion".