Fighting raged in eastern Ukraine for the second straight day on Tuesday as government forces rolled out an offensive against separatist rebels holding the city of Sloviansk, with reports of fatalities on both sides.

Rebels in the town, a fierce separatist stronghold where a military helicopter was shot down last week killing 14 servicemen, said they had brought down a Su-25 attack aircraft and a helicopter, although this was denied by Ukrainian authorities.

Sloviansk People's Mayor Vyacheslav Ponomarev said that on Tuesday two militia people were killed in armed clashes near Sloviansk, adding that "there were no casualties reported among civilians", according to Itar-Tass.

His spokeswoman Stella Khorosheva said that Ukraine's military has amassed armored vehicles and self-propelled mortars and howitzers near the city. The military equipment numbering 100 units includes Grad salvo systems.

At the Ukrainian Parliament's session on Tuesday, Vladimir Medyanik, a lawmaker with the Communist Party, urged the government to immediately stop the bloodshed in the eight-million populated south-eastern region of Ukraine, where the death toll already amounts to dozens or hundreds.

The fighting in Sloviansk followed a daylong firefight on Monday in Luhansk, a rebel-held town further east on the border with Russia, after an attack by separatists on a border guard camp.

At least two people were killed in the center of Luhansk by a blast that rebels said came from a Ukrainian military airstrike, but which the Ukrainians said was caused by a misfire of a heat-seeking missile by the rebels.

Reports of fresh fighting coincided with Ukraine announcing that 59 servicemen had been killed in clashes with rebels since hostilities broke out in the east in April.

"In Donetsk and Luhansk regions, 181 people have been killed and 293 wounded by terrorist activity, including 59 servicemen," general prosecutor Oleh Makhnitsky said at a news conference.

Ukraine's Russian-speaking eastern regions, which border Russia, have been riven with separatist armed rebellions for the past two months.

The Kiev government says the fighting is fomented by Russia, which opposes its pro-Western policies, and accuses Russia of allowing volunteer fighters to cross into Ukraine to fight alongside the rebels.

'Active phase'

Vladyslav Seleznyov, a spokesman for Kiev's military operation, said the government's "anti-terrorist operation" was in its "active phase" near Sloviansk.

"The (separatist) fighters are being blocked. If they refuse to lay down their arms they will be destroyed," he said.

He could not confirm reports of wounded among the government forces around Sloviansk, but he said there were preliminary reports of dead and wounded among the separatists.

"Information that Ukrainian planes and helicopters have been shot down are not true. Yesterday, one of the helicopters received holes from small arms fire," he said.

A Ukrainian military officer, who spoke on condition of anonymity because he wasn't authorized to speak to the media, said one serviceman was killed and 13 others were wounded when their vehicle came under rebel fire near Sloviansk.

Reuters-AP