GLOBAL ECONOMY WEEKAHEAD-EU election casts shadow over euro zone as ECB meeting approaches

* Ukraine election could send jitters through markets

* Eyes on ECB board's signals ahead of June policy meeting

* Housing data due in Britain and United States

* BoE Governor Carney due to speak Tuesday evening

* Japan data due including retail sales, inflation, jobs

By Ana Nicolaci da Costa

LONDON, May 25 (Reuters) - Investors this week will be watching the results of elections that could deal a blow to political parties that are key to reform efforts in the European Union and could also fan instability in Ukraine.

The bonds of some struggling euro zone governments sold off last week as investors worried about expected gains for anti-EU parties in European Parliament votes in Greece and Italy.

In Greece, a strong showing by parties opposed to the terms of its EU-led bailout may hurt the fragile coalition government, potentially paving the way for a new national vote.

In Italy, a poor result for Prime Minister Matteo Renzi's party could undermine his drive for swift reforms, which he promised when he took power in a party coup earlier this year.

The rise of anti-EU parties in northern Europe could make it harder for the European Union to deal quickly with any future resurgence of the euro zone crisis, analysts said.

"It looks like we are going to see the far-right parties making further gains and it is going to make it more difficult for the European authorities to deal with any subsequent euro crisis events," said Victoria Clarke, economist at Investec.

Elections for the European Parliament were held from May 22 to 25.

Ukrainians vote in a presidential election on Sunday and if favourite Petro Poroshenko falls short of an absolute majority, market jitters could grow ahead of a second round of voting on June 15.

Tensions between Ukraine and Russia have escalated in recent months, with Kiev accusing Moscow of sowing deadly disorder in its mostly Russian-speaking east, where pro-Moscow separatists have declared independence and asked to join Russia.

"(If) we head to a second-round vote ... then we might find that we see risk assets suffering in the process until some form of stability has been put in place. So that could be a couple of quite painful weeks and would, if anything, reinforce the case for ECB policy easing on June 5," said Clarke of Investec.

The European Central Bank is widely expected to cut interest rates then, a Reuters poll showed, having clearly flagged that possibility at its last monetary policy meeting.

All this means a three-day ECB forum in Portugal that starts on Sunday and features president Mario Draghi and several ECB board members will be keenly watched by the markets.