Oil prices tumbled yesterday to below $51 a barrel as investors cashed in on recent gains, and doubts grew about the size of output cuts by leading oil exporters.

Benchmark crude for May delivery was down $1.82 to $50.56 by midday in Europe in electronic trading on the New York Mercantile Exchange. The contract dropped $1.96 to settle at $52.38 on Friday.

In London, Brent prices were down $1.56 to $50.42 a barrel on the ICE Futures exchange.