Last Updated Jul 30, 2014 12:45 PM EDT
DONETSK, Ukraine -- Almost two weeks after Malaysia Airlines Flight 17 went down, clashes on Wednesday between Ukrainian forces and separatist rebels again prevented international experts from reaching the crash site to recover remains still baking in midsummer heat in farm fields - deepening frustration for victims' relatives and the governments whose citizens died. Fueling concerns for investigators are claims the separatists are mining the area.
In their latest attempt to get to the wreckage zone, observers from the Organization for Security and Cooperation in Europe left in two vehicles from the rebel-held city of Donetsk but only got as far as the city's outskirts - without investigators from the Netherlands who have been trying to reach the site for four days.
The observers talked with rebels and headed back to Donetsk instead of making what would have been a two-hour journey after being "warned of gunfire on the route and in the surrounding areas," the Dutch team said in a statement.
Ukrainian government security spokesman Andriy Lysenko added to security concerns Wednesday by claiming that separatists "have mined the approaches to this area. This makes the work of the international experts impossible." Even if rebels leave, he said it would take time to remove the mines and make the area safe.
Lysenko was asked at a briefing about concerns that Ukrainian efforts to win back territory were increasing fighting in the area and slowing access. He said that Ukrainian troops weren't conducting operations against separatists near the site, but were trying to cut off their supply lines to force them to leave the area.
The investigative team will nontheless keep trying to reach the site in coming days, but the statement cautioned that "it remains questionable whether the situation will become safer."
That means that almost two weeks after the July 17 disaster, safety concerns and hindrance from the separatists who control the area are still obstructing access to the site and making a desperate wait for victims' relatives even worse.
"We are still waiting and it is a miserable process," said Jasmine Calehr, the grandmother of two Dutch brothers who died in the crash
Foreign governments whose citizens died have complained the site is still not secured and some human remains have not been recovered. International observers say wreckage has been cut, moved or otherwise tampered with.
The Dutch statement said that the team "will nonetheless continue tirelessly in our efforts to achieve our goal: to bring back the victims and their belongings."
Of the 298 who died, 194 were Dutch citizens and Ukraine has asked for their government's help in investigating the crash. Thirty-seven were from Australia. Some 227 coffins have been flown to the Netherlands for identification and investigation. But observers say some remains are still at the site.
Despite her mounting frustration, Calehr said she did not want investigators to go unless it was safe.
"Other people are not supposed to risk their lives. I think our government is doing a terrific job as far as it concerns our pain," she said. "Politically it is not in my hands. Maybe it is not even in their hands. But that there is nobody strong enough to put pressure on a bunch of rebels is very painful."
The U.S. and Ukrainian governments say the Boeing 777 was shot down by a missile fired from areas controlled by pro-Russian separatists who have been fighting the Ukrainian government. The separatists deny shooting down the plane; Russia denies providing the Buk missile launcher and says the Ukrainian military may have shot the plane down.
Elsewhere, Ukrainian forces took control of the town of Avdiyivka, just to the north of the rebel stronghold of Donetsk. The town is near the airport, which has been fought over for weeks by rebels and government forces. Local officials said fighting over the past 24 hours killed 19 people in the region.
Ukrainian forces continue to hold positions around Horlivka, another key town northeast of Donetsk. The city of Donetsk is one of the main strongholds for the insurrection in the east and taking Horlivka would open the way to move against Donetsk, the Ukrainian military has said. Fighting was also happening in Pervomaisk, a town on the edge of the rebel-controlled area.