Ammon News - AMMONNEWS - Ukraine has started voting in a presidential election despite threats by separatists in the country's eastern regions of Donetsk and Luhansk to disrupt what they call an illegitimate vote , Agencies reported.

Sunday's vote began at 0500 GMT, but more than two million illegible voters were expected to be unable to cast their ballots as almost half of the polling stations were blocked in the rebel-held regions.

The election is being seen as an attempt by Ukraine's rulers to stabilise the country following recent political upheavals including the overthrow of its Russia-backed president, which prompted Russia's annexation of Crimean peninsula and a pro-Russia uprising in the east.

Arseniy Yatsenyuk, Ukraine's interim prime minister, has issued an appeal for the country's 36 million voters to turn out in force to "defend Ukraine" in the most important election since independence in 1991.

"This will be the expression of the will of Ukrainians from the west, east, north and south," he said on Saturday.

Pre-election polls suggested that Petro Poroshenko, an experienced politician and the country's seventh richest man, had a chance of winning the elections in the first round.

In case of a second round, he would have to face Yulia Tymoshenko, former prime minister and a long-time rival, who was released from prison in February, following the overthrow of President Viktor Yanukovich.

Ukraine has mobilised more than 55,000 police and 20,000 volunteers to ensure security for the vote, being overseen by 1,200 international monitors.

The country fears a new wave of violence by pro-Russian separatists who started their uprising seven weeks ago and declared independence of the Luhansk and Donetsk regions, prompting clashes with security services and demonstrators for united Ukraine.

At least 150 people died in the unrest.

The West regards the vote as a crucial step in preventing Ukraine from disintegrating further after Russia seized Crimea in March, and has warned Moscow of further sanctions if it disrupts polling.

Russia's President Vladimir Putin - still authorised by parliament to invade Ukraine if necessary to "protect" ethnic Russians - appeared to make a big concession on Friday by saying he was ready to work with the new government in Kiev, Ukraine's capital.

"We understand that the people of Ukraine want their country to emerge from this crisis. We will treat their choice with respect," he said.

Ukraine's new president will be faced with a challenge of finding a common ground with Russia, maintaining close ties with the West without antagonising Moscow, and saving the country's collapsing economy.