Channel 4 is expected to announce plans to cut more than 200 jobs after a decline in demand for advertising.

That equates to 15% of the roughly 1,300 staff currently employed.

In November, the publicly owned British broadcaster’s chief executive said the TV industry was reeling from the worst advertising downturn since 2008.

A spokesperson said “whilst organisational change is never without personal impact, it is a necessary response to allow us to stand out”.

The job cuts are expected to be the worst in the company’s history with the Guardian reporting earlier this month that the channel is seeking to reduce a wage bill of more than £108m a year.

While the restructuring is yet to be announced, the wave of cuts are likely to put pressure on London-based staff after the broadcaster committed to increasing employee numbers outside the capital to 600 by 2025.

The company, which launched in 1982, has already cut its £713m programming budget and shows including SAS: Who Dares Wins, The Big Narstie Show and Steph’s Packed Lunch have been axed.

Alex Mahon, Chanel 4’s chief executive, told the House of Commons culture committee in November that the TV advertising market was is “shock territory”, and, as a result, expected the company to make losses in each of the next two years. It may also have to use some of its emergency £75m credit facility next year.

“We all expected a hard year but we have not seen the predicted recovery in the second half or the fourth quarter,” she said.

“As a result our performance will be affected this year and we will have a deficit this year. I imagine for next year we will look at how to use that debt facility.”

After plans to privatise Channel 4 were dropped by the government last year, the broadcaster has been exploring ways to transition into digital broadcasting in order to compete with online streaming services.

A spokesperson said in a statement that they had to “continue to divest from our linear channels business and simplify our operations to become a leaner organisation”.

It added that it was dealing “with an extremely uncertain economy in the short term and the need to accelerate our transformation to become a genuinely digital public service broadcaster in the long term”.