It's impossible to put an end to the conflict in eastern Ukraine without access the OSCE Special Monitoring Mission (SMM) observers being given access to militant controlled territory, Ukrainian Foreign Minister Pavlo Klimkin has said.

"I sent over 150 addresses to the OSCE regarding the presence of heavy weaponry that was being hidden in various parts of the prohibited zone. However, the problem is that the observers don't have access to occupied territory," Klimkin said at a press conference in Kyiv on Friday.

According to him, if the SMM doesn't get access to occupied territories, Ukraine won't have the slightest assurance of an actual de-escalation.

Klimkin said Ukraine had suggested that weapons with a caliber of less than 100 mm should be withdrawn.

"As for how to control it, the SMM is ready [to do so], but Donetsk and Luhansk are consciously blocking it together with representative of Russian troops that recommend that observers shall not be allowed to the storage of heavy weaponry. This is the key issue and the problem in the position of Russia," Klimkin said.