Russia's ruling party is heading to a convincing victory in Crimea's polls, less than six months after annexing the region.

A preliminary count on Monday showed Crimea's regional branch of the United Russia party was leading with 71.04 percent of votes, after 50 percent of the ballots had been counted, Crimea's electoral commission said.

The ultra-nationalist Liberal Democratic Party of Russia (LDPR), led by firebrand lawyer Vladimir Zhirinovsky who backs the Kremlin, was running second with just over eight percent of the vote.

No other party appeared to have broken the five percent barrier for representation in the Crimean regional parliament, with a turnout of around 52 percent.

The residents of the Black Sea peninsula were voting to select politicians for the parliaments of Crimea and Sevastopol, and for local city councillors.

In polls for the regional parliament of the city of Sevastopol, United Russia had won 76 percent, while LDPR won 7 percent, with 65 percent of the votes counted.

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Russian Prime Minister Dmitry Medvedev, who leads the United Russia, said the vote proved Russia was acting legitimately in Crimea.

"All the participants in the electoral campaign in Crimea have proved to us and our neighbours that power in Russia is based on legal procedures," Medvedev said on Monday in remarks released by the government.

However critics called foul, saying politics in the region had come to resemble the Soviet political landscape, with the election characterised by favoritism towards Russian President Vladimir Putin's ruling party.

"Suddenly, in three months everything became United Russia here," Andrei Brezhnev, head of the Communist Party of Social Justice said.

Ukraine condemned the votes as illegitimate in a statement issued by its foreign ministry.

Ceasefire under strain

The vote came amid renewed fighting in the flashpoint city of Donetsk as six people and an unknown number of soldiers were killed in the bloodiest day of fighting since a ceasefire was drawn up 10 days ago.

"As a result of the shelling, six civilians were killed and 15 people were wounded by shrapnel to varying degrees," Donetsk city council said.

A monitoring team from the Organization for Security and Cooperation in Europe said it was also shelled twice despite a ceasefire being in effect.

The rebels' main leader accused Ukrainian forces of violating the truce repeatedly and suggested it was heading for collapse.

"The government in Kiev is only using the ceasefire to regroup its forces and attack us again," the prime minister of the self-declared Donetsk People's Republic, Alexander Zakharchenko, told the AFP news agency.

The September 5 truce has been broadly holding despite sporadic violations which both sides blame on the other.

Source: Agencies