Eurozone officials meet for further crunch talks on Greece this week amid warnings that time is running out for the country to avoid defaulting on its debts and being jettisoned from the single-currency bloc.

Deputy finance ministers will convene on Wednesday to pave the way for talks among finance chiefs in the Latvian capital, Riga, at the end of the week, a Greek government official told Reuters.

But investors are increasingly sceptical that a rescue deal can be reached between Greece and its creditors. Financial markets do not expect a breakthrough at that meeting of the so-called Eurogroup – the eurozone's finance ministers – and focus is already shifting to early May when Greece is scheduled to repay almost €1bn (£700m) to the International Monetary Fund – a sum most experts say Athens will not be able to raise.

Greece's recently elected leftwing-led government has so far failed to present a package of reforms to the IMF and its eurozone partners that those creditors deem serious enough to unlock the remaining bailout funds.