The ABC’s 11 foreign bureaux will be hit hard by the Coalition’s budget cuts, with plans to scale back the Tokyo, Bangkok, New Delhi and New Zealand offices.

The move is expected to save the ABC’s news budget several million dollars by cutting about 20 international jobs including camera operators, producers and local fixers.

The communications minister, Malcolm Turnbull, is expected to announce the scale of funding cuts to the ABC and the SBS soon, with the ABC likely to lose as much as $50m a year.

Turnbull said on Tuesday he had agreed the size of the cuts. “We’ve come to a conclusion on the level of cuts, yes, and the management of both companies are aware of that and the nature of those cuts will be public before too long,” Turnbull told ABC radio.

Turnbull indicated in September the cuts to the ABC would be as much as $200m. He said the broadcaster could cut its budget by that much and still maintain a quality service, making changes to so-called “back-office” functions only.

But the ABC’s managing director, Mark Scott, disagreed and there are plans to make significant cuts to TV and radio services.

As well as axing the local Friday editions of 7.30 and moving Lateline to News 24 with less resources, the expensive network of foreign correspondents will be targeted.

At the heart of the plan is the creation of four foreign correspondent “hubs” in Washington, London, Jakarta and Beijing that would cover a wider area with journalists and camera crews flying in and out of hot spots.

Sources said the restructure would save on the significant expense of employing a fully-staffed reporting team of journalists, camera operators and producers in Tokyo, Bangkok, New Delhi and New Zealand. The regions would be covered instead by video journalists working from home rather than an established bureau.

The future of the Middle East bureau, which has two reporters and a camera operator covering Jerusalem and Beirut, is also under review.

But the ability of ABC News to cover major events such as the 2011 tsunami in Japan or the recent political upheaval in Bangkok would be severely diminished, former correspondents have warned.

“The ABC has a strategic advantage in international affairs at a time when the commercial networks are only covering Hollywood,” one former foreign correspondent told Guardian Australia.

“It seems idiotic to downgrade the role of the cameramen in Bangkok and Tokyo when they are an absolutely essential element of the coverage.

“We’ve used a cameraman in Bangkok for years. Without him we would have been in danger in such a volatile area. He is a lifesaver. To think that we might move to a model where we would have to survive without him is horrendous.”

In recent years the then-Tokyo correspondent, Mark Willacy, and his camera crew and producers were on the ground to cover the earthquake and tsunami, and subsequent nuclear meltdowns at Fukushima. One source said his unrivalled coverage could not be matched by a video journalist working alone.

There are fears the popular TV program Foreign Correspondent, already cut to 30 weeks a year, may be scaled back again to just 26. Foreign Correspondent is served by the ABC’s network of correspondents posted overseas as well as two based in Sydney.

It is the second time the ABC has attempted to scale back its international coverage. In 2011 most of the recommendations of a two-year review of the ABC’s international operations were abandoned following protests from former foreign correspondents, including Lateline host Tony Jones and the now-retired Peter Cave.

An ABC spokeswoman said no plans had been finalised and that as soon as they were, staff would be informed.