KIEV (Reuters) - Local elections in Ukraine’s port city of Mariupol were called off on Sunday, prompting the ruling party of President Petro Poroshenko and the pro-Russian Opposition Party to blame each other for alleged irregularities in the vote.

Empty ballot boxes are seen at a polling station on the day of regional elections in Mariupol, Donetsk region, Ukraine, October 25, 2015. REUTERS/Maksim Levin -

Mariupol, a city of around 500,000, lies on the coast between the Crimean peninsula, annexed by Russia from Ukraine last year, and separatist-held eastern territory, where a ceasefire between the pro-Russian rebels and Ukrainian forces has largely held since September.

The election spat shows the distrust that persists between Ukraine’s leadership, which has steered the country towards greater integration in Europe, and Ukraine’s pro-Russian faction which retains significant support in the mainly Russian-speaking east.

“According to my information some sort of falsification was being set up and we certainly can’t allow this,” President Petro Poroshenko said as he cast his own vote in Kiev.

He said the Mariupol election should be rescheduled before the end of the year.

In a separate statement, his party blamed the ballot issues in Mariupol on the Opposition Party, which includes many former supporters and allies of ousted pro-Russian president Viktor Yanukovich.

The Opposition Party in turn accused Poroshenko’s party of running a “dirty and unprincipled campaign” and said he was responsible for the elections being cancelled in Mariupol.

The mayoral and council elections are being held across Ukraine, apart from in territories controlled by pro-Russian separatists seeking independence from Kiev and some Ukrainian-controlled towns close to the frontline.

Poroshenko’s ruling party is leading in the polls, but the popularity of his pro-Western government has fallen due perceived slow progress in its implementation of reform amid an economic crisis.

“This is the face of Ukraine. We must make sure and show the world that Ukraine is a free, democratic country and that we work hard so that elections are held according to the best global standards,” he said.

According to a poll from mid-October, 13 percent of voters planned to support Poroshenko’s party in local elections and the next three parties - including Opposition Party - had equal support of 11 percent.

The party of Prime Minister Arseny Yatseniuk is not fielding a single candidate in Sunday’s vote, after support plummeted to 1 percent from over 20 percent one year ago.