At least 251 journalists were jailed for their work in 2018, a report published on Thursday has claimed.

China, Turkey and Egypt imprisoned the highest number of journalists according to the Committee to Protect Journalists' (CPJ) annual report.

The past three years recorded the highest number of jailed reporters since the CPJ report began.

Turkey incarcerated the highest number of journalists this year, with 68 behind bars despite the nation's outcry over the murder of columnist Jamal Khashoggi. For the third consecutive year, every journalist imprisoned in Turkey was facing anti-state charges, the CPJ report said.

Of those jailed, 70 percent were facing anti-state charges or stood accused of aiding groups considered by authorities to be terrorist organisations. False news charges were also on the rise, with 28 reporters held on such charges across Egypt, Cameroon, Rwanda, Morocco and China. The CPJ argued that global rhetoric on "fake news" was being exacerbated by Donald Trump.

China had put a total of 47 journalists behind bars by December 1, at least 10 of whom were being detained without charge, according to the CPJ. This was linked to the reported persecution of the Uighur ethnic minority in the Xinjiang region, where Beijing has been accused of holding up to one million people without trial and operating "re-education centres."

The report showed that at least 25 journalists were being held in Egypt, where authorities were conducting mass trials of reporters. Mohamed Ibrahim, a blogger known as "Mohamed Oxygen" who was imprisoned following his coverage of Egypt's elections, was one of more than 40 defendants in a case where charges included false news.

Saudi Arabia also came under fire in the report for imprisoning 16 journalists, including four women who wrote about women's rights in the kingdom.

With 16 journalists behind bars, Eritrea rounded out the five countries with the most journalists in prison. According to the report, Eritrea imprisoned more journalists than any country in sub-Saharan Africa.

The CPJ report showed that 98 percent of jailed journalists were locals imprisoned by their own governments.

"The terrible global assault on journalists that has intensified in the past few years shows no sign of abating. It is unacceptable that 251 journalists are in jail around the world just for covering the news," CPJ Executive Director Joel Simon said in a press release Thursday.

"The broader cost is being borne by all those who care about the flow of news and information. The tyrants who use imprisonment to impose censorship cannot be allowed to get away with it."