Pro-Russian rebels have paraded military vehicles in front of a cheering crowd in east Ukraine, as fighting continued around Donetsk's airport, piling pressure on a precarious nine-day-old truce.

A group of rebel fighters led a convoy of several battered military vehicles through rebel-held Luhansk on Sunday, as the war-ravaged city had a rare day of jubilation.

Members of the Night Wolves biker gang toured the city as a rapturous crowd of several thousand people came out to wave and cheer.

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Meanwhile, clusters of people lined up in the centre of the city waiting for food rations, a day after Russia sent a 220-truck convoy to residents struggling without water and power for weeks.

The parade came as Kiev accused the separatists of jeopardising a September 5 ceasefire by intensifying their attacks on government positions in the country's east, the scene of five months of deadly combat.

Large clouds of thick black smoke billowed over Donetsk as the sound of sustained shelling and the rattle of automatic gunfire rang out throughout the day, AFP reporters witnessed.

Donetsk council said there had been civilian casualties and described the situation in the city as "critical" but gave no further information.

The fighting appeared to be concentrated near Donetsk airport where the Ukrainian military said it had driven back an overnight assault by about 200 rebels.

"The terrorist actions are threatening the realisation of the Ukrainian president's [Petro Poroshenko] peace plan," National Security and Defence Council spokesman Volodymyr Polyovy said.

However the rebels insisted it was government forces who were to blame for the violence.

"From our side, nobody is shooting but they are breaking the rules, everybody in the world knows it," a rebel commander defending a checkpoint near a village south of Donetsk told the AFP news agency.

A ceasefire deal signed earlier this month is seen as a first step in efforts to draw up a longer term peace deal to end a conflict that has cost more than 2,700 lives.

Source: Agencies