Fighting between Kiev forces and pro-Russian separatists on Wednesday again prevented international investigators reaching the MH17 crash site in Ukraine, the lead Dutch investigator said.

"There will be no convoy with Dutch experts travelling from Donetsk to the site where flight MH17 crashed. The situation along the route is too unsafe," lead investigator Pieter Jaap Aalbersberg said in a statement from the Dutch foreign ministry.aFighting between Ukrainian government forces and pro-Russian separatists on Wednesday prevented international investigators reaching the MH17 crash site for the fourth day in a row, the Dutch team leader said.

"There will be no convoy with Dutch experts travelling from Donetsk to the site where flight MH17 crashed. The situation along the route is too unsafe," lead investigator Pieter Jaap Aalbersberg said in a Dutch foreign ministry statement.

A reconnaissance team from the Organisation for Security and Cooperation in Europe (OSCE) was stopped on its way to the site in eastern Ukraine in the morning, and warned of shots being fired on and around the route there.

"After considering alternative routes or negotiating with the separatists, the OSCE decided to turn back to Donetsk," in rebel-controlled east Ukraine, said the statement.

"The security situation is being assessed on a continuous basis. We will keep trying to reach the crash site in the coming days, but the question is whether it will become any safer."

The Dutch and Australian police mission needs access to the site to recover the remains of some of the 298 victims of the July 17 crash.

Over 200 bodies have already been recovered and sent to the Netherlands for identification. The Netherlands and Australia were home to most of the citizens on the flight, which the West alleges was brought down by separatist rebels.