ROZSYPNE, Ukraine -- Two weeks after a missile brought down Malaysia Airlines Flight 17, an international team of investigators Thursday reached a wreckage site in eastern Ukraine that remains bitterly contested between government forces and pro-Russia separatist rebels.

For the families of the victims, it was an important start in locating and recovering bodies still rotting in the fields and building a case against those who perpetrated the tragedy.

Harun Calehr, the uncle of two young victims of the disaster, said by phone from his home in the U.S. that he was happy investigators had reached the site. But Calehr said he remains concerned that dozens of bodies haven't been retrieved.

"It's been two weeks. I just hope they can get there now and do their job," Calehr said from Houston. "The only thing keeping me sane is being religious, hoping for something positive."

As the investigators -- two apiece from the Netherlands and Australia -- made an initial survey of the area shortly after lunchtime, mortar shells rained down on fields in a nearby village. Despite the lingering signs of risk, the team called their one-hour inspection a success.

For days, clashes along routes to the wreckage site had kept investigators from reaching the area to find and retrieve bodies that have been lying in open fields where midsummer temperatures have hovered around 32 C.

But after negotiations, the investigators were allowed through the final rebel checkpoint before the wreckage site at the village of Rozsypne by a rifle-toting militiaman who then fired a warning shot to prevent reporters from accompanying the convoy on Thursday afternoon.

The militiaman, who gave his name only as Sergei, said there was still fighting in Rozsypne as the Ukrainian army continues an offensive to take back swatches of territory from the rebels.

Australian Federal Police commander Brian McDonald said the visit was only a preliminary survey before more comprehensive recovery work.

"We had a quick inspection of the site. Today was more about an assessment of the site than it was of a search," said McDonald, who was in police uniform.

Up to 80 bodies are still at the site, said Australian Foreign Minister Julie Bishop, speaking to the Australian Broadcasting Corp. from Ukraine.

Ukrainian national security spokesman Andriy Lysenko said a "day of quiet" was declared Thursday in response to a call for a cease-fire from UN Secretary-General Ban Ki-moon.

But Associated Press journalists near the wreckage site reported that clashes were still taking place in the immediate vicinity of where the Boeing 777 came down. Reporters who attempted to reach the area by another route were warned by residents that some nearby roads had been mined.

And AP reporters passing by Hrabove, another village around which fragments of the plane remain uncollected, saw one mortar shell fall on a spot about 150 metres from their car and heard two more hit nearby. It wasn't immediately clear who was responsible for the mortar fire or what the intended target was though Lysenko put the blame on rebels.

The 100-kilometre drive took the investigators and eight officials from the Organization for Security and Cooperation in Europe from the rebel-held city of Donetsk through the town of Debaltseve, which was retaken earlier this week by the government, and later back into rebel territory.

Armoured personnel carriers and light armoured trucks bearing the blue-and-yellow Ukrainian national flag could be seen in and around Debaltseve and residents at one entrance to the town walked along a pontoon erected over the remains of a blown-up bridge.

The OSCE said on Twitter that the team observed a moment of silence upon reaching the scene in remembrance of the victims.

Alexander Hug, deputy head of an OSCE monitoring mission to Ukraine, called the visit a success because the delegation "managed to access the site without any incident."

Ukrainian President Petro Poroshenko's office in a statement urged rebels to comply with a cease-fire spanning an area of 20 kilometres around the wreckage site.

The European Union and the U.S. have formed a united front in accusing Russia of fomenting unrest in eastern Ukraine by supplying weapons to rebels. Russia denies that accusation.

In Brussels, the EU formally adopted economic sanctions designed to pressure Russia to help bring about a peaceful solution to the Ukraine crisis. The measures will take effect Friday.

But back in Donetsk, the rebel's acting political leader, Vladimir Antyufeyev, denied that their movement was being assisted by Moscow.

"Neither I nor (rebel military commander Igor Girkin) knows or has met anybody from the Russian presidential administration," said Antyufeyev, a Russian national.

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Associated Press writers David McHugh and Peter Leonard in Kyiv, John-Thor Dahlburg in Brussels, Yuras Karmanau in Donetsk, and Toby Sterling in Amsterdam, contributed to this report.