Paul Willis faced difficult questions from lawmakers, some of whom are angry that the firm has not been fined in Britain and that motorists have not received compensation, unlike VW owners in the United States, where the company admitted it had used software to cheat tests on diesel emission levels.

"Out of 1.2 million technical measures which have to be applied, as of today, we have applied 470,000 and at the current rate we are applying these measures to 20,000 cars a week," Willis told parliament's transport committee.

Britain's junior transport minister John Hayes said he and his boss, transport minister Chris Grayling, would be travelling to Germany next month to meet their counterparts and seek more information which could lead to an investigation into VW in Britain.

"(We) will go to Berlin next month to meet the minister ... to request that we're provided the detailed technical information that will allow us then, if we chose to, to take further steps," Hayes said.

Hayes also told lawmakers he will soon meet legal representatives of consumers seeking to take legal action against Volkswagen to see what help the government could give them.

In January a British law firm launched legal action seeking thousands of pounds of compensation each for UK drivers affected by the carmaker's emissions scandal, and other firms have since sought to join the move.

(Reporting by Costas Pitas; Editing by Greg Mahlich)