* Russia gets back captured paratroops
* Ukraine had said they were on 'special mission'
* Russian commander criticises Ukraine for delay (Adds quotes, background)
By Mark Trevelyan
MOSCOW, Aug 31 (Reuters) - Ukraine has handed over a group of captured Russian paratroops and Russia has returned 63 Ukrainian soldiers who crossed into its territory last week, 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 and after what he called an unacceptable delay.
Ukraine said last week 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.
The handovers appeared to mark a slight easing in tension between the two countries after a sharp escalation late last week, when the rebels -- supported, according to Kiev, by Russian armoured columns -- opened a new front in the fighting by capturing the southern coastal town of Novoazovsk.
Ukraine had previously said the men were on a "special mission" and had been detained for crossing the border illegally and supporting a "terrorist organisation", the term it uses to refer to the separatists. Its military spokesman mocked the idea they had "got lost like Little Red Riding Hood in the forest".
Ragozin criticised Ukraine's behaviour over the incident.
"I consider it unacceptable that our servicemen were detained by the Ukrainian side for so many days," he said.
Ragozin said Russia, by contrast, had promptly returned 'hundreds' of Ukrainian soldiers who at various times have crossed the border when squeezed by rebel forces. He said the latest group of 63 had entered Russia on Wednesday.
"Our lads are upset about everything that happened. They will all receive the necessary psychological and other kinds of help. The lads will all be OK," Ragozin said.
European Union leaders decided at a summit on Saturday to draw up proposals within a week for further sanctions against Russia in the light of mounting evidence of its military involvement in Ukraine, something Moscow continues to deny. (Reporting by Mark Trevelyan; Editing by Larry King)