Brexiteer Ms Patel, a former Cabinet minister, said the European Commission’s hardline stance in the exit talks was “unreasonable”.
She also urged the Prime Minister to step up preparations for a no-deal Brexit, saying the UK must “be ready” for such an outcome.
In a fiery speech at the Tory conference yesterday, she said: “We need to say ‘no’ to the EU and say: ‘No deal means no cash’.
“The European Union has spurned the Government’s generous overtures already.
“We must say no to their bullying and no to their unreasonable demands, and no to the £40bn divorce settlement.
“Over the next six months, we must prepare our country for all eventualities.”
Ms Patel, the ex-International Development Secretary, also hit out at Mrs May’s Chequers proposal for Brexit.
She told the BrexitCentral fringe event: “We must not accept Chequers, and if that means no-deal, we should be ready for it.
“That means getting turbo-charging our economy to give us the economic liberalism that we need to be a free and independent country.
“That’s a vision that we must see going forward. We’re not just standing up for Brexit, we’re going to carry on campaigning.
“I have every faith and confidence in this country, and in the spirit of the British people.
“In the crucial weeks and months ahead, we must stand up for our country and defend the democratic decision made in the referendum.”
Speaking at the same event, fellow Tory MP Jacob Rees-Mogg also said the UK should refuse to pay the EU’s divorce bill.
He told party activists: “There is £40billion of your hard earned money going to the European Union which we save.
If we leave on World Trade Organisation (WTO) terms we are under no obligation to pay a penny – not a brass farthing.
“We would not owe them anything and we would immediately be able to trade with the world.”