MOSCOW — Russia blamed authorities in Kiev on Monday for the violence in eastern Ukraine, accusing them of trying to ignite a civil war in the region, but a top US diplomat warned that Russia has ‘‘days, not weeks’’ to abide by an international accord aimed at stemming the crisis.
The United States has said it will order new economic sanctions against Russian officials and entities if Moscow doesn’t follow through on the provisions in last week’s accord.
Gregory Pyatt, the US ambassador to Ukraine, said it was still too early to tell whether the deal would succeed, but he added, ‘‘The ball is really in Moscow’s court.’’
‘‘There needs to be concrete results,’’ Pyatt told reporters in Kiev, the Ukrainian capital. He said the United States would make a decision on whether the agreement is working within days.
Vice President Joe Biden arrived Monday in Kiev to confer with political leaders, activist groups, and diplomats on the crisis, in which pro-Russia militants are continuing to occupy government buildings in the east in defiance of the central government.
Biden is bringing US economic assistance to Kiev as well as warnings to Russian President Vladimir Putin that future intervention in Ukraine’s volatile east will incur new costs.
But Foreign Minister Sergey Lavrov said Moscow will intervene militarily if bloodshed continues — even as Ukrainian officials accuse Russia of stirring it up.
‘‘There has been a surge in appeals to Russia to save them from this outrage,’’ Lavrov told a news conference here, invoking a time-honored Russian rationale for military intervention in another country. ‘‘We are being put into an extremely complex position.’’
‘‘Those who are deliberately pursuing a civil war, in a possible attempt to start a big, serious bloody conflict, are pursuing a criminal policy,’’ he said. “And we will not only condemn this policy but will also stop it.’’
Lavrov said Kiev was ‘‘flagrantly’’ disregarding its obligations under an agreement reached Thursday in Geneva. Russia demands that a protest camp at Kiev’s Independence Square, known as the Maidan, be disbanded before further steps toward a resolution can be taken, he said.
The square was the center of protests against pro-Russia president Viktor Yanukovych, who was ousted in February.
Biden is the most senior administration official to visit Ukraine since its crisis with Russia began two months ago, leading to Russia’s annexation of Ukraine’s autonomous Crimea region in March.
A senior American official said the vice president would meet with top Ukrainian officials Tuesday and reveal a US technical support package aimed at boosting the country’s economy, energy sector, and political reform efforts before presidential and mayoral elections May 25.
Under the Geneva agreement, which has the approval of the United States and the European Union, armed groups are supposed to vacate the buildings they have seized. But in eastern Ukraine, there has been no movement so far in that direction.
Lavrov also took a shot at Washington on Monday, saying there was no way Russia could be effectively isolated.
Ukraine’s leaders fear Putin is looking for an excuse to take more direct action in the nation’s east, where many residents speak Russian and distrust central authorities in Kiev.
‘‘President Putin has a dream to restore the Soviet Union, and every day he goes further and further, and God knows where is the final destination,’’ Ukraine’s acting prime minister, Arseniy Yatsenyuk, said Sunday on NBC’s ‘‘Meet the Press.’’ The United States says that about 40,000 Russian troops are gathered along Russia’s border with Ukraine.
Biden will meet Tuesday with Yatsenyuk and Oleksandr Turchynov, the acting president. He is also scheduled to meet with legislators from across the country and democracy activists before returning to Washington on Tuesday night.
There was a burst of violence Sunday in a village outside Slovyansk, in which at least three local people were killed during a shootout at a checkpoint that was manned by pro-Russia troops. Militants and Russian media said two of the attackers also were killed.
Ukrainian and Russian officials each blamed the other for instigating the attack.
The White House said it was trying to determine who was responsible and had no independent verification of what happened.
‘‘Overall, we are concerned about the situation there, and we urge paramilitary groups throughout the eastern and southern parts of Ukraine to lay down their weapons and depart the buildings that they have occupied, as was called for in the accord signed in Geneva last week,’’ White House spokesman Jay Carney said.
Even as officials sorted through this latest disturbance, the State Department sought to build a public case against Russia for the wider unrest, the Associated Press reported.
The United States asserted on Monday that publicly available photographs from Twitter and other media show that some of the troops in eastern Ukraine are Russian special forces, and officials said the photos support their argument that Moscow is using its military to stir unrest in Ukraine.