Eleven members of the Special Monitoring Mission (SMM) to Ukraine were detained on Wednesday, the OSCE reports.
The group was on its way to Dnipropetrovsk, Ukraine’s fourth largest city with a population of roughly one million, from Donetsk city when they were stopped at a road block in Marinka.
Contact with the monitors was then lost for several hours before being reestablished when the group returned to Donetsk.
The nationalities of the group are American, Austrian, Bulgarian, Dutch, Finnish, Italian, Norwegian, Polish, Russian and Slovak.
The OSCE lost contact with another SMM group, consisting of four members, on Monday and has not heard from them since.
In April, a separate team of observers were detained for a week by pro-Russian activists in Slovyansk, the separatists stronghold in Donetsk region, before being released.
“It’s war, it’s civil war.”
Ukraine has been in a crisis for nearly eight months that threatens to tear the country in half.
In November of 2013, pro-EU activists took to the streets in Kiev to protests against former Ukrainian President Viktor Yanukovych against a deal he favored for closer ties to Russia.
The protest turned violent when the former president passed an anti-protest law which led to clashes between the protesters and police officers in and around Maidan, Kiev’s Independent Square, that resulted in over 100 deaths and the ousting of Mr. Yanukovych.
Shortly later, Russian soldiers, referred to as “little green men” because of the green uniforms they wore that bore no insignia, invaded Crimea, raising fears that Russia would repeat in Ukraine what it did to Georgia in 2008.
In March, Moscow annexed the peninsula after referendums on joining the Kremlin were held in the region.
Kiev and the West refused to recognized the referendum and annexation as legitimate but there was little the Ukrainian government could do. Majority of the population in Crimea are ethnic Russians and are in favor of being apart of Russia.
After the annexation of Crimea, the Kremlin continued to stress its right to intervene in Ukraine if it felt the rights of the Russian-speaking population were violated, leading to fears that Moscow would order a military invasion.
The support pro-Russian activists were receiving from Moscow led to separatists uprisings throughout eastern Ukraine.
The Kiev authorities then ordered for “anti-terror” military operations to squash the rebellion.
On May 11, pro-Russian leaders in Donetsk and Luhansk held referendums for greater self-rule and then declared a “People’s Republic”.
Just two hours later, Denis Pushilin, the leader of the “Donetsk People’s Republic” asked for the region to be annexed by Russia.
However, Russian President Vladimir Putin declined Mr. Pushilin’s request and seemed to have flip-flopped from his previous aggressive position.
In recent weeks, Mr. Putin has stressed his desire for peace and stability in Ukraine and has said that Moscow will work with the Ukrainian government to make his desires a reality.
Meanwhile, the military operations conducted by Kiev authorities have continued and resulted in the deaths of dozens of people.
Newly elected Ukrainian President Petro Poroshenko has promised to crush the separatists uprising in the east of the country “within hours”, suggesting that the “anti-terrorists” operations will escalate into further, bloodier violence.
Moscow, however, has demanded that Ukraine end its military operations.
Over 100 people have been killed at Donetsk Sergey Prokofiev International Airport in the past three days in the bloodiest fighting between Ukrainian military forces and anti-Kiev separatists.
One agonized and tormented middle-aged man that is a resident of Donetsk described the situation in Ukraine to BBC, saying: “It’s war, it’s civil war.”