Russian Foreign Minister Sergei Lavrov and his German counterpart Frank-Walter Steinmeier discussed on Monday the detention in Ukraine of observers from the Organization for Security and Cooperation in Europe (OSCE), the Russian Foreign Ministry said.
The ministry gave no further details of the call, which it said was a German initiative.
Earlier on Monday, Germany urged Moscow to use its influence on pro-Russian separatists in eastern Ukraine to secure the release of observers from the OSCE.
Chancellor Angela Merkel's spokesman Steffen Seibert said Berlin condemned the detention of the team, which includes four Germans, calling it "against the law and without justification".
The release of one of the eight hostages on medical grounds was "a positive step" but the other seven must also be freed "immediately, unconditionally and unharmed", said Seibert.
Pro-Russian separatists
Armed pro-Russian separatists who took control of the police headquarters in the east Ukrainian town of Kostyantynivka have also seized the town administration building, a spokesman for the regional government said.
"I think it's the usual demands, the same as in other towns, the scenario doesn't change: a referendum and a federal system of government," said Ilya Suzdaliev, a spokesman for the Donetsk region administration, which includes Kostyantynivka.
A Reuters photographer in Kostyantynivka said he could see about 20 gunmen controlling the town administration building. He said they were wearing camouflage fatigues and masks.
Earlier, pro-Russian separatists seized the local police headquarters in the eastern Ukrainian city of Kostyantynivka, a spokeswoman for the Ukrainian Interior Ministry said on Monday.
"At 6:00 a.m. (0300 GMT) about 30 separatists came to the local police headquarters and occupied the ground floor. Negotiations are underway with the local police chief. We do not know what their demands are," said Laryssa Volkova, interior ministry spokeswoman.
On Sunday, Pro-Russian rebels paraded European monitors they are holding in eastern Ukraine, freeing one but saying they had no plans to release another seven as the United States and Europe prepared new sanctions against Moscow.
Kharkiv's Mayor
Gennady Kernes, the mayor of Ukraine's second-biggest city, Kharkiv, is in hospital undergoing emerging surgery after being shot in the back, Interfax Ukraina news agency quoted the mayor's spokeswoman as saying on Monday.
"The doctors are fighting to save his life," the agency quoted the spokeswoman, Tatiana Gruzinskaya, as saying.
Defense imports
President Vladimir Putin said on Monday that Russia will be able to replace any defense industry imports lost due to the Ukraine crisis with its own products despite the close ties between arms and military equipment makers in Russia and Ukraine.
Putin told lawmakers he believed the motive behind any Western sanctions targeting the Russian defense sector would be a desire to undermine Russia's efforts to compensate for a reduction in imports from Ukraine.
Sanctions
The United States on Monday imposed sanctions against seven Russian government officials and 17 companies linked to Russian President Vladimir Putin in its latest action to punish Moscow for its intervention in Ukraine.
The White House said the seven Russians, including two from Putin's inner circle, are now subject to a freeze on any assets they hold in the United States and a ban on U.S. travel.
In addition, the United States will deny export license applications for any high-technology items that could contribute to Russian military capabilities. The Commerce and State Departments will revoke any existing export licenses that meet these conditions, the White House said.
REUTERS