DNA Bioscience said last night that it would continue to use David Blunkett’s name in its marketing as questions emerged over whether it held the correct paperwork to bid for official work.

The United Kingdom Accreditation Service told BBC2’s Newsnight that the company was not properly accredited to be on a Department of Constitutional Affairs list, which gives access to court work.

The programme reported that in March one of DNA Bioscience’s rivals complained to the DCA that the company should not be on the list, because it did not have an accredited laboratory in Britain.

Despite the discrepancy, the firm said it would continue to use Mr Blunkett’s name in negotiating future deals with government departments and other clients.

Its defiance will disturb ministers who had hoped that Mr Blunkett’s statement would be the last time he was mentioned in connection with the company that knows how to stay in the headlines. Last night the directors were trying to contact the minister to see what he would do with the £15,000 of shares he had put in trust for his sons, saying that they had been given no warning of their former colleague’s plans. “We will be looking into what happens next, but there was never anything underhand about our involvement and neither we, nor he, has anything to apologise for,” a spokesman said.

Avi Lasarow, the company’s founder and managing director, said: “As someone who wants to get our name out there, perhaps as the McDonald’s of DNA, how bad can it be to have your company thrown into the column inches?” Far from being embarrassed about the fuss over links with Mr Blunkett, last night the company was eulogising his contribution to its business successes.

He may have been on the payroll for only a fortnight as a non-executive director but a spokesman described the minister’s advice as “invaluable”.

Aware of the sensitivity of paternity testing, given his own troubles at the time with his former lover, Kimberley Quinn, Mr Blunkett apparently shared his private thoughts on this type of business.

In a statement, his former colleagues said: “The company deals on a daily basis with sensitive issues regarding paternity testing and Mr Blunkett’s experiences and knowledge enabled him to contribute to the development of the company and assist us in the communication of these sensitive and emotional issues.”

A spokesman said the advice was confidential. “We are certainly not hiding our relationship with him,” he said. “Although he was with us for only a short period there is no need for us not to refer to him in business negotiations.”

The company reportedly cited Mr Blunkett’s name, however, in discussions with the Law Centres Federation, which was set up by the Government. Steve Hynes, director of LCF, recalled how the DNA firm brought up its well-known board member to emphasise its credibility. So far none of DNA Bioscience’s clients has expressed concerns about the furore and staff do not expect it to jeopardise future deals.

Founded three years ago by Mr Lasarow, 29, a former banker, the firm supplies kits for determining parentage. Insiders said it was aware of the publicity value of hiring Mr Blunkett when it offered him a non-executive directorship this year. In the final stages of the election campaign, when he joined on April 21, Mr Blunkett found time to visit DNA Bioscience’s offices and was featured in publicity photographs.

The company offered him the chance to buy a dozen shares — about 3 per cent of the firm. He was reportedly told that the value would soar if it secured more contracts with Whitehall. The company was reportedly surprised when Mr Blunkett returned to Cabinet office, and he resigned his directorship that day, May 6, 2005. “He is still a part of our history, and someone who has been vital to our growth,” the spokesman said.

Times Recommends

• Donor organ allowed child’s own heart to heal
• Michael Jackson: Not the final chapter
• Brüno toned down for 15 rating