The government must keep its promise to introduce new corporate killing legislation during the next parliament, trade unions and leading personal injury law firm Thompsons have demanded.

Deputy prime minister John Prescott is pledged to get tough with companies who put their workers' lives in danger. A bill to introduce a law that would make company directors criminally liable for deaths caused by management failure was expected to be included in the Queen's Speech.

But according to press reports Home Office minister Charles Clarke has admitted that it is unlikely that draft legislation will be ready in time.

The Home Office is still considering submissions to its consultation on reforming the law on involuntary manslaughter, which ended on 1 September. It says that the government is still committed to creating an offence of corporate manslaughter, but that there are "many different views to be taken into account".

Clarke is reported to fear that a new law on corporate manslaughter risks creating scapegoats and employers' organisations such as the CBI and CIPD, all opposed the new offence in their submissions to the government.

Mick Rix, general secretary of train drivers' union Aslef, urged the government not to back away from its pledge in the face of representations from Railtrack chief executive Gerald Corbett and other company bosses.

"The government's proposals for legislation already fall short of making owners, managing directors and senior personnel criminally liable for fatal accidents at work," Rix said. "It is a disgrace that just weeks after yet another tragedy on our railways in the shape of the Hatfield disaster the Home Office is still dithering over making company directors directly responsible for breaches of health and safety that result in the death of employees."

Andy Gilchrist, general secretary of the Fire Brigades' Union, added: "The government assured us that the law would change, and would change soon. Ministers have listened for too long to the pleadings of the employers and all the while men are dying."

The joint Aslef/FBU/Thompsons submission to the Home Office consultation paper called for company bosses to face prison sentences for breaches of health and safety that result in the death of employees. The government's consultation paper fell short of doing so.