The prime minister has been criticised after it emerged that she previously called for MPs to have the right to veto the UK's negotiations with the EU.
In 2007 Theresa May said ministers should gain Parliamentary approval before talks with the European Union.
Mrs May is now resisting pressure to give Parliament a vote on her plans for Brexit prior to EU negotiations.
Downing Street said her 2007 comments related to how ministers negotiated policy while inside the EU.
In June the UK voted to leave the EU, prompting the resignation of former prime minister David Cameron, who was replaced by Mrs May.
'Impossible to override'
In a pamphlet published in 2007 Mrs May, who as a Conservative MP was then in opposition, argued it should be "impossible to override" Parliament.
She said "ministers should have to set out their negotiating positions" to a Commons committee "and gain its approval" before talks were held with the EU.
Ministers who failed to do so should resign, she said.
In October this year Downing Street said it was "very likely" MPs would be able to vote on the final Brexit agreement reached between the UK and the European Union.
But campaigners, including many who backed Remain in the referendum, have been calling for Parliament to be given a vote on the government's negotiating strategy.
The former shadow minister for Europe, Labour MP Pat McFadden, said Mrs May could no longer deny Parliament a meaningful role in what Brexit means.
He told the Times: "This paper shows that the prime minister does in fact believe that ministers should get parliamentary approval for negotiating strategies with Europe.
"Sooner or later, ministers will realise that they can't support Brexit in the name of parliamentary sovereignty and deny parliament a meaningful role in what Brexit means."
Mrs May has promised to trigger Article 50 of the Lisbon Treaty - beginning two years of formal exit negotiations with the EU - by the end of March.
But the prime minister opposes a vote before Article 50, saying those calling for one are "trying to subvert" the outcome of June's referendum.
Nick Clegg, the former deputy prime minister who speaks for the Liberal Democrats on Brexit, told the Independent: "I agree entirely with what Theresa May wrote in 2007, that it should be 'impossible to over-ride' Parliament and that 'ministers should have to set out their negotiating positions'.
"What a pity she appears to have changed her mind."
Downing Street said the situation now was about negotiating an entirely new relationship with the EU and was based on the mandate given in the referendum by British voters.