LONDON (Reuters) - U.S. President Donald Trump is part of a three-pronged attempt to undermine the European Union, Guy Verhofstadt, one of the EU’s top officials and its chief Brexit negotiator, said on Monday.

Guy Verhofstadt, European Parliament's chief Brexit negotiator, sits for an interview with Reuters in New York, U.S., January 23, 2017 while promoting his book "Europe's Last Chance". REUTERS/Daniel Bases

The other two threats were from radicalised Islam and from Russian President Vladimir Putin, who Verhofstadt said was also working against the progress of the EU project.

“We have a third front, for the moment, undermining the European Union, and it is Donald Trump,” Verhofstadt said in a speech at the Chatham House think-tank.

“Trump spoke very favourably of the fact that also other countries will want to break away from the European Union, and that he hoped for a disintegration of the European Union.”

Verhofstadt served for nine years as prime minister of Belgium, and has served in the European Parliament since 2009.

He said that the European Union had severe problems, saying it was in a “poly-crisis”, but nevertheless argued that the solution was for greater co-operation between states.

“A disintegration of the Union would be a disaster ... not only for Europe but also I think for our allies and for the world.”

Some Britons criticised the appointment of Verhofstadt as the negotiator on behalf of the EU Parliament in Britain’s forthcoming talks to leave the bloc, with those who campaigned to leave the EU describing him as a “fanatical” federalist.

He again expressed his regret at Britain’s decision, and said that the Europe would not accept “cherry-picking” of EU policies without Britain accepting the liabilities and obligations that came with them.

However, he said that security issues, which have come under scrutiny after a spate of attacks in European cities in the past 18 months, should be negotiated separately to economic issues such as the European single market or trade.

“What we are saying is that you have the whole economic membership withdrawal agreement, that’s one thing,” he said.

“Separately from this, there is the whole internal and external security issue. And I don’t think it is a wise thing for there to be a trade-off between the one and the other.”