A total of 230,000 people have fled their homes during the spiraling armed conflict in eastern Ukraine, the United Nations refugee agency said Friday.

UNHCR spokesman Dan McNorton told reporters that the number of people who have left the conflict zone for other Ukrainian regions was now close to 100,000, while some 130,000 had crossed the border into Russia.

Three hours after the digging began, a piece of white sackcloth was seen in the soil.

A few minutes later, four bodies were being recovered from the hole.

Australian troops plan to join a police contingent in helping secure the Flight MH17 crash site in Ukraine, Prime Minister Tony Abbott said Friday, while stressing the mission would be humanitarian in nature.

Abbott has been highly critical of the response on the ground to the downing of the Malaysia Airlines plane, which was carrying 298 people when it was apparently shot down in rebel-held eastern Ukraine.

The United States on Thursday said it had evidence Russian forces were firing artillery from inside Russia on Ukrainian troops, in what officials called a "clear escalation" of the conflict.

Moscow is also planning to "deliver heavier and more powerful multiple rocket launchers" to the pro-Russian separatist forces in Ukraine, U.S. deputy State Department spokeswoman Marie Harf said.

Russian President Vladimir Putin's military intervention in Ukraine is fanning nationalist sentiments that could spread across the region with dangerous, unpredictable consequences, the U.S. military's top officer said Thursday.

General Martin Dempsey, the chairman of the U.S. Joint Chiefs of Staff, said Putin was pursuing an "aggressive" agenda that flouts sovereignty and seeks to address alleged grievances harbored by Moscow since the demise of the Soviet Union.

A Russian court on Thursday jailed a radical opposition leader Sergei Udaltsov to four and a half years for organizing "mass riots" ahead of Vladimir Putin's inauguration as president in 2012.

Judge Alexander Zamashnyuk sentenced both Udaltsov and his political ally Leonid Razvozzhayev to four and a half years in a corrective labor camp for organizing a rally against Putin and plotting further unrest.

Dutch investigators into the shooting down over Ukraine of flight MH17 said Thursday they had downloaded data from the black box flight recorder and that it had not been tampered with.

"No evidence or indications of manipulation of the recorder was found," the Dutch Safety Board (OVV) said in a statement.

A Canadian warship with a crew of 250 headed Thursday to the Mediterranean where it will join a NATO fleet providing increased security in Eastern Europe amid tensions with Russia over Ukraine.

HMCS Toronto, which is equipped with torpedoes, anti-air and anti-ship missiles as well as a Sea King helicopter, will replace HMCS Regina, which has been part of the NATO operation since May.

The European Union will add to its sanctions list 15 Ukrainian and Russian individuals and 18 entities over their role in the Ukraine crisis, an EU source said Thursday.

The source said the 18 entities will be made up of nine companies and nine institutions, such as the local authorities set up by pro-Russian rebels that have proclaimed independence in eastern Ukraine.

The U.S. national aviation authority lifted a ban on American flights to Israel late Wednesday, but warned of a "very fluid situation" amid intense fighting in the Gaza Strip.

After a rocket fired by Hamas militants in the Gaza Strip struck a house just north of Israel's main airport in Tel Aviv, the Federal Administration Agency imposed the ban on Tuesday and then renewed it midday Wednesday.