Three-quarters of the UK's railways are now owned by foreign companies, according to a report by the Rail, Maritime and Transport Union (RMT).
Figures show that 20 out of the country's 27 private rail contracts are owned by foreign state-owned or backed railways, mainly from France, Germany and Holland.
The union said last week's decision to award the Scotrail franchise to Dutch state-owned firm Abellio showed overseas firms now "dominated" the UK's railways and called for a Parliamentary inquiry into rail ownership.
RMT general secretary Mick Cash said: "The true scale of the way the railways here in Britain are being used as a cash cow to hold down fares and improve services across the rest of Europe will shock passengers as they prepare for another week of being crammed into creaking cattle trucks while being bled dry when they pay for their ticket.
"With the planned reprivatisation of the East Coast Mainline by this rotten Government, we are rapidly heading towards a situation where almost the entire train operation in Britain is in the hands of overseas companies sucking out profits to benefit their own domestic transport services."
A Department for Transport spokesman said: "These claims are completely misleading. All companies have been awarded franchises through open competitions precisely because they offer the best deal for UK passengers and taxpayers.
"The fact is that franchising has transformed Britain's railways. An industry once in decline is now experiencing record growth, with passenger journeys doubling since privatisation. "