International experts began recovery work at MH17’s crash site in eastern Ukraine, despite ongoing clashes in the area between government forces and pro-Russian rebels. (Reuters)

Crash site investigators in Ukraine found more human remains Friday among the first small patch of wreckage they searched in the village where the fuselage of the Malaysia Airlines plane landed.

Pieter-Jaap Aalbersberg, head of the Dutch-led recovery team, said no bodies were found, only remains. They are expected to take at least three weeks to complete their work, he said, longer if delays arise due to fighting between government troops and rebels who control the crash site.

After cancelling visits to the site for most of the week while negotiating with rebels for access, Friday marked the first day a sizeable contingent of forensics experts was able to start combing through the debris searching for human remains and personal possessions of the 298 passengers and crew who died.

The body parts, whose condition Aalbersberg declined to describe out of respect for the surviving family members, were taken away in ambulances. They will be transferred to refrigerated train cars, and eventually flown to the Netherlands for identification, he said.

But the team’s accomplishments at the crash site were overshadowed by continuing tensions in eastern Ukraine, and in Washington and Moscow.

President Obama spoke with Russian President Vladimir Putin on Friday for the first time since Malaysia Airlines Flight 17 was downed July 17 by what is believed to have been a missile fired from territory held by the pro-Russian rebels.

According to the White House, Obama expressed his concerns about Russia’s support for the separatists in Ukraine, and urged a diplomatic solution. It said they agreed to keep the channels of communication open.

In the Kremlin version of the call, Putin warned Obama that economic sanctions against Russia related to its involvement in Ukraine are “counterproductive,” and could damage U.S.-Russia cooperation and general global stability.

Vice President Biden talked on the phone with Ukrainian President Poroshenko, and announced $8 million in U.S. aid for border security, including surveillance equipment, small boats and patrol vehicles. The Pentagon has separately asked for $19 million more for training.

In Ukraine, heavy fighting was reported near the rebel strongholds of Donetsk and Luhansk. Shortly after daybreak, a Ukrainian convoy of paratroopers was ambushed by insurgents in the town of Shakhtorsk, about 12 miles from the crash site. At least 10 Ukrainian soldiers were killed and 13 wounded, according to military spokesman Andriy Lysenko.

The team of 70 Dutch and Australian experts arrived at the crash site around 11:30 and observed a moment of silence before beginning their work, Aalsbersberg said.

The investigators, who have identified five debris fields where they think they are most likely to find remains and possessions, worked on only a small section of wreckage, measuring a little more than 15 feet square in the village of Hrabove, where the fuselage fell. Aalbersberg said they hope to return over the weekend with up to five squads, totaling 100 experts, and expand their search to some of the other target areas. Divers, sniffer dogs and cranes may be deployed, he said.

The experts are relocating their base in eastern Ukraine from the rebel-held city of Donetsk. Though it is only about 40 miles away on a direct route, teams had to take a roundabout journey to the crash site, crossing front lines four times. As a result, it took them more than four hours to reach their destination. Now, they will be in the government-controlled town of Soledar, from which their travel time will be much shorter, and they will have more time to spend working at the crash site.

Angus Houston, a special envoy from Australia, expressed his gratitude to all the parties that helped the team gain access after four days of delay. But he pointedly praised the Ukrainian government and monitors from the Organization for Security and Cooperation in Europe, who negotiated with rebels to facilitate access. Houston omitted any mention of the insurgents.

Bill Branigin and Karen DeYoung in Washington contributed to this report.