Prices of British steel are soaring as unprofitable producers aim to shut factories
Unions have called for the High Speed 2 rail link to be built using British steel to avoid soaring prices.
Steelworkers have warned prices of the product are soaring as unprofitable producers try to close factories and shift production abroad.
Liam Fox has said the Government will take its time to evaluate British steel-maker Tata's decision to close three plants in Britain, including its sites in Redcar and Scunthorpe.
He told BBC1's Andrew Marr show that HS2's trains, which will run from London to Birmingham and the North's cities from 2033, would have 'most likely' be assembled using British steel.
Members of the Communication Workers Union have accused the Government of 'flip-flopping' on HS2 and slammed Liam Fox for 'playing on the fears of workers' as a result of a move to produce the railway line domestically.
CWU deputy general secretary Terry Pullinger said: 'The Tata steel crisis is hitting workers on the shop floor now, with costly steel factories closed, the threat of supplier consolidation, and worsening prospects for the future.
'Yet, just days after the crisis escalated, with a national company threatening to close three of the largest plants in the UK, the Government is playing on the fears of workers.
'We've seen little sign from the Government that they are giving their full support to steel-making and steel workers in Britain.
'If ministers want the steel industry and its workers to have any hope, they've got to put money on the table for the Government to explore alternative, low carbon options for the HS2 line.'
When asked on the Andrew Marr Show if there would be a line made with British steel in place of British steel, Liam Fox said: 'We'll make our trains most likely in Britain, in Wales or in North Wales.
'And we'll have security arrangements for the supply.
'The private sector now is very depressed. Steelmakers are reducing their working days, their production, their fleet of trains are down.
'And we are committed at Government level to get the industry going, getting support, getting security arrangements in place and helping to get what we say is the potential for a massive increase in steel-making in this country.
'That's our objective.'
Liam Fox, the International Trade Secretary, said: 'We'll make our trains most likely in Britain, in Wales or in North Wales. And we'll have security arrangements for the supply. The private sector now is very depressed'
Earlier this month, Mr Fox attended Tata Steel's European headquarters to meet the firm's CEO.
The steel firm employs more than 10,000 people across the UK.
Last month Sir Richard Branson and Business Secretary Greg Clark spoke to Tata workers at its Derbyshire plant.
The closure of the three factories will leave the UK with 12 active steelworks, down from 15 two years ago.
Liam Fox is attending an important G20 summit in Argentina where Britain is represented by Foreign Secretary Jeremy Hunt.