NETWORK Rail and maintenance firm Balfour Beatty were preparing to defend themselves and their employees last night against charges of manslaughter in connection with the Hatfield train disaster.

The Crown Prosecution Service said six managers from the two companies had been charged with four counts of manslaughter due to gross negligence and an offence under the Health and Safety at Work Act.

Network Rail, the successor to Railtrack, and Balfour have also been summonsed on manslaughter offences.

Another six men received summonses under health and safety legislation, including the former chief executive of Railtrack, Gerald Corbett, who is now chairman of store chain Woolworths.

The maximum sentence for people convicted of gross negligence manslaughter is life in prison, while the companies face unlimited fines if found guilty.

Only two large companies - P and O European Ferries, over the Zeebrugge ferry disaster, and Great Western Railways, over the Southall crash - have been charged with manslaughter in the past, and both cases failed.

Four people died on October 17, 2000, when a GNER express train was derailed half a mile south of Hatfield station, in Hertfordshire.

The London to Leeds train derailed because of a broken rail, which Railtrack and Balfour Beatty allegedly knew about beforehand.

Solicitors representing the injured and families of the victims welcomed news of the prosecutions, as did rail safety groups and unions.

But Balfour Beatty criticised the decision to press charges and defended its safety record.

The company said: "We see no justification for manslaughter charges to be brought against our maintenance business or its former employees.

"The charge of manslaughter against our maintenance business will be firmly defended as we see no plausible basis for it in law or on the evidence.

"The individuals charged will have the company's fullest support in their defence of the charges against them."

Network Rail also pledged to defend the company and its employees against the charges.

It said: "As the company stated last week, we believe that our employees conduct their duties to the best of their abilities with the sole intention of delivering a safe, reliable and efficient railway network."

Mr Corbett said it was likely to be several years before the case was heard and he would defend himself vigorously.

He said: "I was the chief executive when something went wrong, and that is why I immediately tendered my resignation. But taking responsibility for one's organisation does not necessarily mean that I accept that the rail breaking was in any sense attributable to neglect on my part."

Crown Prosecutor Andrew Faiers said the decision to press charges was based on substantial evidence.

The six men who were all charged with four offences of manslaughter and one health and safety offence were named by the CPS along with their job titles at the time of the crash.

They were Charles Pollard, director of the London North-East Zone of Railtrack; Alistair Cook, infrastructure contracts manager of the London North-East Zone of Railtrack; Sean Fugill, area asset manager of the London North-East Zone (South) of Railtrack; Anthony Walker, regional director until 11 August 2000 of Balfour Beatty; Nicholas Jeffries, civil engineer for Balfour Beatty; and Keith Lea, track engineer of the London North Eastern Zone of Railtrack.

The six who were summonsed under the Health and Safety at Work Act were also listed with their job titles at the time of the crash.

They were Gerald Corbett, chief executive of Railtrack; Christopher Leah, director of safety and operations of Railtrack; Stephen Huxley, managing director until August 31, 2000, of Balfour Beatty; Kenneth Hedley, a track engineer for Balfour Beatty; Vernon Bullen, King's Cross area maintenance engineer for Balfour Beatty; and Keith Hughes, an acting track engineer for Balfour Beatty.

All those charged have been summonsed to appear before Central Hertfordshire Magistrates' Court on Monday.