An OSCE spokeswoman said rebels who met the OSCE observers and experts had fired into the air.
Thomas Greminger, the council chairman, said: "They did not have the kind of access that they expected. They did not have the freedom of movement that they need to do their job. The crash site is not sealed off."
Greminger is also Switzerland's ambassador to the European rights and security watchdog.
He said a team of OSCE monitors had stayed at the crash site for about 75 minutes and then set off back to Donetsk, but would try again on Saturday.
World leaders have called for a rapid investigation into the shooting down of the airliner, which could mark a pivotal moment in deteriorating relations between Russia and the West.