MOSCOW (REUTERS, AFP) - Ukraine has handed over a group of captured Russian paratroops and Russia has returned 63 Ukrainian soldiers who crossed into its territory last week as fighting intensified, Russian news agencies quoted a paratroop commander as saying.

RIA news agency quoted Russian Major-General Alexei Ragozin as saying the paratroops had been handed back after "very difficult" negotiations.

"The talks were not easy, but common sense prevailed and everything turned out well," the deputy commander of the Russian paratroop forces, said Maj-Gen Ragozin.

"The most important is that all of our boys are back with us in Russia," he said.

Ukraine said on Monday it had captured 10 paratroops and presented them to the press as evidence that the Russian military is fighting alongside pro-Moscow separatist rebels in eastern Ukraine. Russia said the men had crossed an unmarked section of the border by accident.

Another ten paratroopers were injured and two killed from that unit when they came under attack by Ukrainian government forces, according to Russia's NTV television.

The capture of the paratroopers, and reports of secret funerals near Russian military bases, put Moscow on the spot regarding its involvement in a lightning counter-offensive by rag-tag pro-Russian rebels that has seen them push back Ukrainian soldiers.

Russia continued to deny that its regular troops were deployed in Ukraine or that it had supplied equipment to the rebels, but Nato said on Thursday that Moscow had well over 1,000 troops on the ground in Ukraine and 20,000 massed by the border.

The 10 Russian paratroopers handed back were sent to Moscow for medical and psychological treatment, NTV reported.