LONDON, April 27 -- British Prime Minister Theresa May said Thursday night she needed a stronger majority in the House of Commons to strengthen her negotiating hand with Brussels as Britain prepares to leave the European Union.

May was responding to a speech made hours earlier to German politicians by Chancellor Angela Merkel, saying the comments showed how tough the Brexit negotiations will be.

In her speech, Merkel said Britain's relationship with the EU would be a different relationship, adding: "A third country, which is what the UK will be, cannot and will not have the same rights as an EU member state. All 27 EU countries and the EU institutions agree about that," she told the Germany's lower House of Parliament, the Bundestag.

Responding to the comments, May told party supporters at an election rally in the city of Leeds in Yorkshire: "We have seen Chancellor Merkel's comments today. She says the UK has illusions about the process, and that the 27 member states of the European Union agree. We can see how tough those negotiations are going to be at times.

"Yet our opponents are already seeking to disrupt those negotiations, at the same time as 27 other European countries line up to oppose us.

"That approach can only mean one thing, uncertainty and instability, bringing grave risk to our growing economy with higher taxes, fewer jobs, more waste and more debt. We need the strongest possible hand, the strongest possible mandate and the strongest possible leadership as we go into those talks."

Merkel said some people in Britain had illusions that trade talks with the EU could take place at the same time as negotiating the terms Britain's EU exit.

"It would be a waste of time to maintain illusions that the two sets of negotiations could be held simultaneously," Merkel added.

Britain wants talks about the terms of Brexit to take place alongside negotiating a future trading relationship with the EU and it's 27 member states, ahead of a final separation in two years time.

EU leaders meet on Saturday to adopt a joint negotiating position on Brexit, but there will be no official talks between Brussels and London until after the British general election on June 8.

Opinion polls continue to give May and her Conservative government a clear lead with an increased majority. Addressing a rally in the traditional Labour Party heartlands of northern England is seen as a move by May to win support for the Conservatives from Labour, led by Jeremy Corbyn.

May, speaking at the rally in Leeds, said the general election is the most important election Britain has faced in her lifetime.

"In this election, every single vote will count. And every person in this country has a positive reason to lend me their vote," she said.

May was questioned by the media at the rally following comments made earlier by Foreign Secretary Boris Johnson that Britain could join the U.S. in a military strike on Syria.

May responded by saying it was a hypothetical issue as there were no proposals for a further strike on Syria.

Asked by a journalist if Johnson would stay as foreign secretary if she wins the June 8 election, May replied "Boris is doing a great job as foreign secretary."