Train carrying MH17 bodies reaches government-held Ukrainian city

* Victims' bodies to be handed to Netherlands

* Some remains still at crash site - OSCE

* EU ministers delay action on further sanctions

* Russia challenges accusations that separatists behind disaster (Adds address by Malaysian PM to parliament)

By Anton Zverev and Peter Graff

DONETSK, Ukraine, July 22 (Reuters) - A train carrying the remains of many of the 298 victims of Malaysia Airlines flight MH17 arrived in a Ukrainian government-held city on Tuesday on the first leg of their final journey home to be reclaimed by their families.

Five refrigerated wagons containing 200 body bags reached the city of Kharkiv after pro-Russian separatists agreed to hand over the plane's black boxes to Malaysian authorities and the bodies to the Netherlands, where many victims had lived.

The train slowly rolled into the grounds of an arms industry plant, where the remains are due to be unloaded and flown to the Netherlands for the lengthy process of identification. A spokeswoman for a Dutch team of forensic experts in Kharkiv said departure was not expected before Wednesday.

A representative of the OSCE European security watchdog said there were still human remains left where the Boeing 777 hit the ground in eastern Ukraine last Thursday. "We did not observe any recovery activity in place," spokesman Michael Bociurkiw said after his group inspected the site earlier in the day.

The jet was flying from Amsterdam to Kuala Lumpur when it was shot down near Donetsk, a stronghold of pro-Russian rebels, where fighting with Ukrainian troops flared again on Tuesday.

Western governments have threatened Russia with broader sanctions for what they say is its backing of the militia. However, they are struggling to agree a response, and European Union ministers meeting in Brussels on Tuesday delayed action for a few days.

Russian President Vladimir Putin said he would urge the separatists to allow a full investigation which the Netherlands said it would lead. Malaysia said it would send the black boxes to a British lab for analysis.

"Here they are, the black boxes," separatist leader Aleksander Borodai told journalists at the headquarters of his self-proclaimed Donetsk People's Republic as an armed rebel placed the boxes on a desk.

Malaysian Prime Minister Najib Razak, speaking to parliament in Kuala Lumpur on Wednesday, maintained his stand that blame should not be apportioned pending an investigation.

"A few hours after MH17 crashed, officials in the U.S. and Ukraine claimed it was shot down," Najib said.

"If that is true, we criticise the party believed to be responsible. However, we are not pointing fingers at anyone at this stage, until evidence has really been obtained."