Japan’s oldest English-language newspaper has sparked anger among staff and readers after revising its description of wartime sex slaves and forced labourers from the Korean peninsula.

In a decision that critics said aligned it with the conservative agenda of the prime minister, Shinzō Abe, the Japan Times said it had used terms “that could have been potentially misleading” when reporting on the contentious subjects.

It was the latest media row about how to define notorious parts of the country’s wartime record.

The Japan Times, which marked its 120th anniversary last year, said in an editor’s note in Friday’s edition that it would ditch the commonly used term “forced labour” to describe Koreans who were made to work in Japanese mines and factories during its 1910-45 colonial rule over the Korean peninsula.

South Korea says there were nearly 150,000 victims of wartime forced labour, 5,000 of whom are alive.

The Japan Times said: “The term ‘forced labour’ has been used to refer to labourers who were recruited before and during world war two to work for Japanese companies. However, because the conditions they worked under or how these workers were recruited varied, we will henceforth refer to them as ‘wartime labourers.’”

The explanation appeared at the foot of an article about the South Korean supreme court’s decision this week to order Mitsubishi Heavy Industries to compensate 10 former forced labourers. The ruling, and a similar decision last month, have soured ties between Tokyo and Seoul, with Japan’s foreign minister, Tarō Kōno, calling them “totally unacceptable”.

The Japan Times, whose motto is ‘all the news without fear or favour,’ said it would also alter its description of the comfort women – a euphemism for tens of thousands of girls and women, mainly from the Korean peninsula, who were forced to work in Japanese military brothels before and during the war.

The newspaper noted that it had previously described the victims as “women who were forced to provide sex for Japanese troops before and during world war two”.

But it added: “Because the experiences of comfort women in different areas throughout the course of the war varied widely, from today, we will refer to ‘comfort women’ as ‘women who worked in wartime brothels, including those who did so against their will, to provide sex to Japanese soldiers’.”

Reporters and editors at the paper’s Tokyo headquarters greeted the decision with a mixture of anger and consternation. “People are pretty angry about the change and the fact that we were not consulted,” a Japan Times employee told the Guardian.

The revision has added to concern that sections of the media are bowing to pressure from rightwing politicians and activists to rewrite Japan’s wartime history and portray its actions on the Asian mainland in a more favourable light.

That movement has gathered pace since 2014, when the liberal Asahi Shimbun retracted articles about wartime sex slaves it had run in the 1980s and 90s that it admitted had been based on false testimony by Seiji Yoshida, a former soldier.

Campaigners pointed out that Yoshida’s discredited testimony did not in itself disprove the existence of wartime sex slaves.

Two months later, the Yomiuri Shimbun, a conservative broadsheet with a daily circulation of more than 10m, apologised for its previous use of the term “sex slaves” in its English-language edition. The newspaper said it would instead use the more ambiguous wording “so-called comfort women”.

Editors in the English-language division of NHK, Japan’s public broadcaster, are banned from using the term “sex slaves” and must instead refer to them as “people referred to as wartime comfort women”.

The editorial shift by the Japan Times comes soon after South Korea said it would dissolve a Japanese-funded foundation to support survivors, sparking outrage in Tokyo. The move, which in effect terminated a 2015 agreement to settle the countries’ impasse over sexual slavery, drew an immediate rebuke from Japan.

The Japan Times has been contacted for comment.