The number of dole claimants has shown its strongest rate in a decade, as an increase in unemployment saw the number of manufacturing workers shrink to its lowest amount since at least 1984.

The number of claimants of Jobseeker's Allowance rose by 9,700 last month to 950,800, the Office for National Statistics said. The jump was the biggest since December 1992, when Britain was in the depths of its worst recession since World War II.

Unemployment as measured by International Labour Organisation techniques, which the government preferred, has also risen, the ONS said, standing 36,000 higher in the February to April period than the three months before. The unemployment rate was up 0.1 percentage points at 5.1 per cent.

The figures came as the number of factory workers shrank by 3.7 per cent over the year to 3.53 million.

"This is the lowest level since comparable records began," the ONS said, adding that all manufacturing sectors had seen job losses.

However, the report warned against calling time on Britain's low-unemployment spell.

"Trend asessments this month are that the employment rate is levelling off, but the unemployment rate is still falling slightly," the ONS said.

The number of people in employment rose by 51,000 over the three months to 27.9 million. 

But growth in earnings, remained "moderate", at 3.2 per cent. While public sector wages were, in April, rising at an annual rate of 5.2 per cent, private sector salaries were showing 2.7 per cent gains.

The private sector figure compares with the 3.0 per cent reported in March, and an underlying inflation rate of 3.0 per cent.

The weaker earnings data, a signal of lower inflation, raised hopes of a cut in interest rates at the Bank of England's July meeting.

"It is shaping up to be quite a close call," one City analyst said.