According to a memo from Mark Kelsey, CEO of RBI UK, seen by Journalism.co.uk, the cuts will focus on the group's magazine and support arms, which have been 'most hard-hit by the downturn'.
"Over the last two months in particular, trading has deteriorated at an unprecedented rate across almost all of our key advertising markets," said Kelsey in the memo.
"We have been working through every cost line across the business, including implementing some targeted redundancies, to find savings to protect our business and keep our vulnerable magazines viable, but it is clear that we also now need to reduce staff numbers further."
If enough volunteers are not found by the end of May, RBI, which publishes New Scientist and Flight Global, will propose compulsory redundancies, the memo said.
"This launch comes in the context of an extraordinarily difficult recession and RBI UK feels that it is a preferable first step to reducing staff costs," an RBI spokeswoman confirmed to Journalism.co.uk.
In January the publisher announced plans for 35 redundancies in the UK. National Union of Journalist (NUJ) members at the group voted against industrial action over these cuts in February.
(Updated 5:11pm) RBI has confirmed to Journalism.co.uk that the new cuts are in addition to the 35 redundancies previously announced.
In December parent company Reed Elsevier terminated the sale of magazine arm RBI, as a result of 'the recent deterioration in macro-economic outlook and poor credit market conditions'.
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