Russia Demands 'Urgent Steps' to End Fighting in East Ukraine as OSCE Says Contact Lost with 2nd Team near Donetsk

Russia on Wednesday said there was no justification to Ukraine's offensive against eastern separatists and demanded "urgent steps" be taken to end the seven-week campaign.

Russian Foreign Minister Sergei Lavrov told his German counterpart Frank-Walter Steinmeier by telephone that "there can be no justification for the punitive operation" and called for "urgent steps to be taken to end the bloodshed and to launch a dialogue between the Ukrainian people, including on the subject of sweeping constitutional reform".

Meanwhile on ground, the European security body OSCE said that a second group of observers had been detained near the east Ukrainian city of Donetsk, a day after it lost contact with another team.

"At around noon today the OSCE Special Monitoring Mission (SMM) to Ukraine lost contact with some members of its Donetsk-based team. The team was west of Donetsk City on its way to Dnipropetrovsk when contact was lost," the Organization for Security and Co-operation in Europe said in a statement.

The OSCE said the monitors were "detained".

"At around 19:00 contact was re-established when the group returned to Donetsk," it added.

In its statement, the OSCE said the team "consists of 11 international SMM members, travelling in three vehicles. The monitors were stopped at a road block in Marinka."

It added that the observers included two Bulgarians and one each from Austria, the Netherlands, Finland, Italy, Norway, Poland, Russia, Slovakia and the U.S.

"We are continuing with our efforts and utilizing our contacts on the ground. The Ukrainian government, as well as regional authorities, have been informed of the situation," the statement continued.

On Tuesday, the OSCE said it had lost contact with a first group of four observers.

An official in Vienna said the team -- a Dane, an Estonian, a Turk and a Swiss national -- was detained at a checkpoint in eastern Ukraine 40 minutes before contact was lost.

"They're still missing, there still hasn't been any contact with them," the OSCE spokesperson said Wednesday.

The Ukrainian foreign ministry has accused rebels of holding them, but the Turkish foreign ministry said the team appeared to be "safe and sound".

The Special Monitoring Mission currently has some 280 unarmed civilian members in Ukraine, whose job is to meet with local and national authorities as well as ethnic and religious groups and non-governmental organisations.