Dell has warned that its second-quarter earnings will fall short of Wall Street expectations, blaming a slow commercial market and aggressive pricing. 

Shares in the world's biggest computer company fell by 14 per cent after the Texas-based firm made the latest in a series of profit warnings.

Revenue growth at Dell has slowed in recent quarters, amid tougher competition from its closest rival HP. 

The warning follows several negative stories about Dell, including complaints about poor after-sales services, criticisms over misleading adverts, a Dell blog that shared its name with a porn site, and a run-in with the Office of Fair Trading over its consumer terms and conditions. 

Dell recently simplified its pricing after customers complained about the complicated process of finding out the sale price of a computer. The firm unveiled plans in May to cut prices and increase spending on customer service.

Analysts said that these moves could help improve customer relations, but were unlikely to increase sales significantly.

In a statement released today, Dell insisted that it is seeing "positive results and will continue to invest to drive a superior customer experience".

However it blamed "aggressive pricing in a slowing commercial market worldwide" for its disappointing revenues.