(Adds Lysenko comments)
DONETSK, Ukraine, July 24 (Reuters) - Artillery fire echoed in the south and northwest of rebel-held Donetsk in eastern Ukraine on Thursday and one district near the city was without electricity as Ukrainian forces pressed a military campaign against pro-Russian separatists.
The rebels ordered the removal of all vehicles in a square near the train station, and local authorities said damage to dozens of electricity substations had left at least one district, called Petrovsky, without electricity.
Ukraine's army has forced the rebels back to their two main strongholds of Donetsk and Luhansk, taking villages and suburbs around them, and officials said they were continuing to abandon positions outside the cities.
"We are noticing the further strengthening ... of attacking positions and defence, as well as the movement of armoured vehicles into towns around Donetsk, in Horlivka and Ilovaisk," the Ukrainian military said in a statement on Thursday.
Two Ukrainian fighter jets were shot down on Wednesday, not far from the site where a Malaysian airliner was brought down last week, killing all 298 people on board.
Citing preliminary information, Kiev said the missiles that brought down at least one of the fighter jets on Wednesday could have been fired from Russia. On Thursday, a spokesman for Ukraine's Security Council softened the line, saying Kiev was not "accusing anyone" and was only looking at possible versions.
The spokesman, Andriy Lysenko, said the jets' pilots survived the crash.
On Thursday, the Russian Defence Ministry denied the accusation, saying it was an attempt "to mislead the public", Russia's Interfax news agency reported, citing an official. (Reporting by Lina Kushch and Natalia Zinets, writing by Elizabeth Piper, editing by Timothy Heritage)