Around two-thirds of Dysons sales now come from overseas

The Wiltshire-based firm, headed by inventor James Dyson, said pre-tax profits in 2004 were �102.9m, more than double 2003's figure.

Dyson, one of the UK's best-known brands, entered the US market two years ago and sold 891,000 vacuum cleaners there in 2004.

Mr Dyson said: "America is a notoriously difficult market to crack."

Dyson claims to have around one-fifth of the US market by value for upright and cylinder vacuum cleaners.

Offshore manufacturing

Overall revenues were up by more than 50% at �426m in 2004.

But Dyson performance in the UK was not quite so strong - its share of the market by value fell from 43.6% in 2003 to 40%.

The company said around two-thirds of its sales now came from overseas.

Dyson shifted production of its vacuum cleaners from Malmesbury in Wiltshire to Malaysia in 2002.

At the time, Mr Dyson said he had been forced to shift offshore because of lower costs. He also cited the fact that both component suppliers and some of the cleaners' biggest markets were based in the region.

This was followed by an announcement in 2003 that production of Dyson's washing machines would also be transferred to Asia.

Around 1,200 people still work at the company's head office and research facilities in Wiltshire.