Infrastructure company Metronet sacked the employees after a cleaner discovered 111 beer and cider cans, plus an empty brandy bottle, in a mess room at Farringdon station.
The Rail, Maritime and Transport union reacted furiously yesterday, claiming the evidence against the employees was purely circumstantial.
The RMT's regional organiser, Bobby Law, said a Metronet manager washed around 80 of the bottles and cans before taking pictures of them. The union believes they had been gathering dust in a roof compartment of the mess room for months or even years.
Bob Crow, general secretary of the RMT, pointed out that none of the employees tested positive for drugs or alcohol. He said the union had reported Metronet to the British Transport police for failing to investigate the incident adequately.
"Unless these workers are reinstated within seven days I will be recommending a ballot of our Metronet members for industrial action," said Mr Crow.
Metronet is responsible for the upkeep of nine lines including the Bakerloo, Central, Victoria, Circle, District and Hammersmith & City.
A strike would add to commuters' woes, compounding a 48-hour go-slow on safety grounds scheduled to begin on December 9 and an ongoing dispute on the Hammersmith & City line over the sacking of a driver caught playing squash while on sick leave.
A Metronet spokesman said yesterday's dismissals followed disciplinary proceed ings against 13 workers, of whom eight were allowed to keep their jobs. He said the company had a "reasonable belief" that the remaining five had breached a zero tolerance policy on alcohol.
Metronet said only a handful of overnight track workers used the mess room, although the RMT disputed this. The company insisted that "best before" dates on the cans and bottles indicated that they were relatively new.
The mayor of London, Ken Livingstone, yesterday urged tube unions to avoid strikes and to work with him on improving conditions on the network.
"They will never be in a better position in terms of leadership and management of the tube system," he said. "They will never have another mayor who is more sympathetic in terms of trade union rights than myself."
