More than 2.5 million workers are now covered by the Skills Pledge, with 400 employers signed up to the scheme.

Interserve Plc, VT Group Plc, EDS UK and Reliance Security Group Ltd are the latest four companies to make the voluntary commitment to help all their employees gain at least a Level 2 qualification - the equivalent of five GCSEs at A - C grade.

The latest figures suggest that the voluntary pledge is gaining momentum after what seemed to be a slow start following its June launch.

Skills Minister David Lammy, said that employers who signed up to the pledge showed “the type of excellence we are looking to be the norm across the country”.

“In today’s global economy having a highly skilled workforce is an economic necessity, not an optional extra,” Lammy said. “To achieve our ambition for world class skills we are giving employers a powerful voice in designing the training they require, and delivering it where and when they want it to meet their needs."

Employers that make a commitment to the Skills Pledge have support from Skills Brokers, as part of the Learning and Skills Council’s Train to Gain service, to help them draw up their plans, and if appropriate to find good training providers and access free literacy and numeracy and first full Level 2 qualification courses.

The Leitch Review of Skills, published in December 2006, warned that the UK must raise its game on skills at all levels if it is to sustain and improve its position in the global economy.

It set a target of increasing the proportion of adults with Level 2 qualifications to 90% by 2020, and called on the government to make training compulsory if the UK was not making sufficient progress by 2010.