Moscow called for unspecified “emergency” measures Wednesday to halt the violence in eastern Ukraine, after pro-Russian militias suffered the heaviest casualties of their separatist insurgency.

“It’s necessary to take emergency steps to stop the bloodshed and start an inclusive internal Ukrainian dialogue,” Foreign Minister Sergei Lavrov told his old German counterpart Frank-Walter Steinmeier by phone, according to the ministry’s website. “There’s no excuse” for military action in the southeastern part of the country, Lavrov said.

Ukraine stepped up air patrols over the eastern city of Donetsk Wednesday as a convoy of pro-Russian rebels moved through the city with an anti-aircraft gun in tow, threatening renewed violence after dozens of militants were killed in a government operation to retake the area’s biggest airport.

Both sides suffered casualties as rebels stormed a National Guard base in Luhansk last night, the Interior Ministry said on its website, without further details.

President-elect Petro Poroshenko has vowed to wipe out the insurgents and re-establish order after winning office May 25. He’s faced with trying to stabilize an economy the European Bank for Reconstruction and Development expects to shrink 7 percent this year while reclaiming swaths of the Donetsk and Luhansk regions captured by pro-Russian militias.

Russia is reducing the number of soldiers stationed on its border with Ukraine to about 20,000 from about 50,000, the press service of Ukraine’s border guards said yesterday. The Russian troops are leaving behind military infrastructure, suggesting they may return, the service said.

Even so, a “threatening, capable” Russian force remains “poised along the Ukrainian border,” Col. Steve Warren, a spokesman for the Pentagon, told reporters Wednesday.

The Foreign Ministry in Moscow said earlier that Russia is being asked to provide humanitarian aid to people in eastern Ukraine affected by the conflict. Russia wants Ukraine’s help delivering supplies across the border and expects “the fastest possible answer” to its proposal, the ministry said on its website.

“We will consider it, but Ukraine doesn’t have a shortage of anything,” Yevhen Perebyinis, a spokesman for Ukraine’s Foreign Ministry, said by phone. “Pro-Russian militias aren’t allowing us to deliver goods. People can’t get salaries and pensions. State institutions can’t work because of them.”

Russian President Vladimir Putin, who has repeatedly denied aiding the insurgency, told Italian Prime Minister Matteo Renzi in a phone call on Tuesday that Ukraine’s military operations must stop. Lavrov repeated that position in a phone call with U.S. Secretary of State John Kerry, the Foreign Ministry in Moscow said Wednesday.

“Russia’s goal was and is to keep Ukraine so unstable that we accept everything that the Russians want,” Poroshenko said in an interview with German newspaper Bild. “I have no doubt that Putin can end the fighting with his direct influence.”

As the violence continued, Ukraine stopped short of accepting an European Union proposal to reach a debt and price deal for natural gas from Russia and avert a threatened shutoff. Russia, the world’s largest supplier of the fuel, has twice cut gas flows to Ukraine since Putin came to power in 2000, leading to shortages throughout Europe.

Under the EU plan, Ukraine’s state energy company, NAK Naftogaz Ukrainy, would pay Russian gas exporter OAO Gazprom $2 billion by Friday and a further $500 million by June 7. That would partially cover Ukraine’s outstanding debt, which Gazprom Chief Executive Officer Alexey Miller said will reach $5.2 billion by June 7.

Ukraine’s government is “ready to clean the bill” and “pay the arrears” of its bill, Prime Minister Arseniy Yatsenyuk said in Berlin Wednesday. The country is seeking a market-based price of $250-$350 per 1,000 cubic meters, he said.

Russia is ready to discuss the price and is willing to consider canceling a requirement for Ukraine to prepay for the fuel if the country pays Gazprom in accordance with a May 26 agreement, the Energy Ministry in Moscow said in an e-mailed statement.

About 15 percent of Europe’s gas supply flows from Russia through Ukraine, which is counting on $17 billion from the International Monetary Fund to avoid bankruptcy. Ukraine, which gets half of its gas from Russia, will only start paying its debt after Gazprom agrees to cut its price, said Energy Minister Yuri Prodan.

Gazprom raised the price it charges Ukraine by 81 percent to $486 per 1,000 cubic meters after Kremlin-backed President Viktor Yanukovych fled the country in February. Prodan said Ukraine is willing to pay $268.50, according to Interfax.

Yatsenyuk is scheduled to hold talks with German Chancellor Angela Merkel Thursday in Berlin, where he will attend a conference on energy security.

EU leaders meeting in Brussels on Tuesday decided to put off further sanctions on Russia after Putin showed a willingness to work with Ukraine’s new leader and pulled back some troops from the border.

“The possibility of de-escalation is here, finally,” French President Francois Hollande told reporters after the summit ended. “But we still need this strict reminder.”

In their final statement, the leaders said the EU was working on “possible targeted measures” and agreed “to continue preparations” in case further steps are needed.

Since Putin annexed Ukraine’s southern Crimea region in March, the EU has blacklisted 83 Russian and Ukrainian officials and two companies.

President Barack Obama, who has imposed sanctions on people close to Putin, called Poroshenko this week to congratulate him on his victory and offer “the full support of the United States as he seeks to unify and move his country forward,” according to an e-mailed statement from the White House. The two leaders agreed to continue talking when Obama visits Europe next week.