BUCHAREST: Romania`s pro-EU Prime Minister Marcel Ciolacu on Monday announced his resignation, deepening political turmoil a day after a far-right candidate topped the first round of a tense presidential vote rerun.

Far-right EU critic George Simion topped Sunday`s election first round, while the ruling coalition`s candidate narrowly lost out to Bucharest`s mayor, Nicusor Dan, for the second spot.

With the ruling coalition`s candidate Crin Antonescu knocked out of the running, Ciolacu would likely have been replaced by the new president, who appoints the premier.

Ciolacu said his party would leave the ruling coalition but would probably hold on until after the election run-off, scheduled for May 18 and which is being closely watched by Brussels and Washington.

Romania, which borders war-torn Ukraine, is an EU and Nato member.

His Social Democrats (PSD) party leaving the ruling coalition `implicitly leads to my resignation as prime minister`, Ciolacu, 57, told reporters after a party meeting.

`We saw how Romanians voted yesterday (Sunday), which means that the ruling coalition has no legitimacy, at least in this formula,` he added.-AFP