Former Greek prime minister George Papandreou has called for Britain to remain in the European Union ahead of the referendum in June, saying a unified Europe will be better prepared to tackle global issues such as the refugee crisis.

"I would say being together is being stronger, whether it is a refugee problem today, or tomorrow, another type of threat like the financial crisis," Papandreou, who led Greece from 2009 until 2011, told IBTimes UK at the 2016 Global Education and Skills Forum.

"The more we work together, the more we are able to have our voice heard and influence the world. We are living in a global world now. We are not living in our isolated corners. So the question is, how do we deal with global issues? The more we work together, the more we can cooperate."

Papandreou, who resigned in November 2011 during the Greek government debt crisis, said it was essential that Britain raised issues concerning red tape in Brussels.

"There are issues in European Union, and the UK has raised them – that is good. The UK has said: 'what do we do with the big bureaucracy in Brussels? Maybe we need to have more democratic control over that?' I would agree with them," Papandreou said.

"So let's work together in trying to change Europe and make it what we want it to be. Stay with us, and help us make the change in Europe so we can be a real strong power."

The European Union is facing three key issues: the eurozone financial crisis, the refugee crisis and a potential crisis should the UK decide to leave the union.

Speaking at a press conference in Brussels at the beginning of this year, European Commission president Jean-Claude Juncker said there are "multiple" crises facing the EU, but said the 28-nation bloc would pull through. He cited the Greek debt crisis, refugee crisis, Ukraine conflict and the UK's forthcoming referendum are "vulnerabilities" facing the EU.

"The number of unresolved problems have been piling up and I'm sure further problems will be added to the list, we've got the issue of the UK," Juncker said. "I don't have too many illusions but the year ahead because everything's going to be difficult. But I'm not going to give up, I reject the idea that this is somehow the beginning of the end."