Ammon News - AMMONNEWS - Pro-Russian separatists have shot down a Ukrainian military transport plane 10km from the eastern city of Luhansk, killing several people on board, the defence ministry has said.

Ukrainian officials offered condolences on Saturday to the families of the "killed soldiers", but did not say how many had died in the attack.

A ministry statement said "terrorists" had "cynically" fired a large-calibre machine gun hitting a Ukrainian air force Ilyushin-76 as it was about to land at Luhansk airport, the AFP news agency reported.

Al Jazeera's Kim Vinnell, reporting from Donetsk, said that up to 40 people may have been on board the plane when it was shot down.

The airport is the only area of the city still under Ukrainian government control, Vinnell said.

Lugansk, which is close to the Russian border, is the main city of one of two eastern regions hit by violence and which has declared its independence from Kiev.

'Anti-terrorist' clampdown

On Friday morning, Ukrainian troops, including special forces, launched an operation to expel pro-Moscow fighters in the port city of Mariupol, leaving five rebels and two soldiers dead.

Ukrainian Interior Minister Arsen Avakov called the raid a success, and witnesses said that at least four separatists had been arrested, the AP news agency reported.

Ukraine and the West accuse Russia of supplying separatists with weapons, supplies and fighters.

Also on Friday, the US confirmed earlier reports that a convoy of armoured vehicles, including three Russian T-64 tanks, had moved in to Ukraine from Russia and were now in rebel hands.

US State Department spokeswoman Marie Harf said Washington had information that Russia had accumulated tanks of a type no longer used by its own forces in southwest Russia, and some had recently left the area.

Harf said the alleged transfer of arms from Russia to rebels in Ukraine was "unacceptable".

An "anti-terrorist" clampdown by Ukrainian armed forces has left at least 270 people dead in eastern Ukraine over the past two months.

*Agencies