Reuters, which has been hit by a sharp fall in subscriptions for its information services, said the move reflects changing market rates for IT staff.
About 260 contractors in the UK and 140 contractors in the US face rate cuts of up to 20% from 1 September.
The cuts will affect contractors in all positions in Reuters, including developers, business analysts and support staff, with those on the highest salaries receiving the greatest cuts.
Further rate cuts are expected to follow in 100 Reuters locations world-wide. "Obviously this is a first step. We have conducted a review in the US and UK and we are conducting a review of contractor rates across other areas and countries," the company said.
Reuters said its research showed that 75% of employers have made similar rate cuts, and it is simply following the market trend.
However, there are signs that contractor rates are beginning to stabilise, particularly for highly skilled staff, such as project managers, systems architects and senior developers.
"We have seen rate cuts of between 15% and 20% over the past 19 months," said Paul Smith, group marketing director at consultancy Harvey Nash. "But we know it is coming to an end. We have had a consistent period when we have not seen any erosion."
Michael Bennett, director of IT recruitment firm Best International, said, "A couple of major organisations have cut rates publicly but they seem to have done this late on in the cycle. We feel we are through the bottom of the market. We are seeing an upturn in our business."
However, experts predict that rates for helpdesk and support staff could continue to come under pressure.