Russian combat soldiers, along with heavy military equipment, have entered separatist-held regions of eastern Ukraine in the last few days, a senior Nato official has confirmed.
Speaking at a news conference in Bulgaria, Nato Allied Command Operations Supreme Allied Commander Europe US Air Force general Philip Breedlove said: "We have seen columns of Russian equipment, primarily Russian tanks, Russian artillery, Russian air defence systems and Russian combat troops, entering into Ukraine.
"We do not have a good picture at this time of how many. We agree that there are multiple columns that we have seen," Breedlove added, noting that their goal may be to consolidate the separatist enclaves.
"It is our first guess that these forces will go in to make this a more contiguous, more whole and capable pocket of land in order to then hold onto it long-term."
The Organization for Security and Cooperation in Europe (OSCE) has already reported seeing unmarked convoys of weapons and other military systems entering the separatist-held areas of eastern Ukraine in recent days.
However, Russia has denied allegations that any of its soldiers or equipment have crossed into the region.
Russian Defence Ministry spokesperson major general Igor Konashenkov was quoted by local media as saying: "We have stressed repeatedly that there have never been and there are no facts behind the regular blasts of hot air from Brussels regarding the supposed presence of Russian armed forces in Ukraine.
"We have stopped paying attention to Nato Supreme Allied Commander Europe Gen Philip Breedlove's unfounded statements alleging that he observed Russian military convoys invading Ukraine."
Meanwhile, the Ukrainian Government has announced plans to redeploy soldiers in the special operation areas of the Donetsk and Luhansk regions.
Ukrainian Defence Minister Stepan Poltorak was quoted by RIA Novosti as saying: "We are redeploying our forces just in case unforeseeable actions occur. We have the situation under control and we're ready to react.
"The situation in Donbas is complex, but stable. We know about the increase in forces from the armed groups and Russia, and we're waiting for unexpected actions."
Ukraine had withdrawn its troops from the region as part of a ceasefire deal reached with pro-Russia rebels on 5 September to end the crisis, which has reportedly killed more than 4,000 people since April.
Image: Pro-Russian rebels remove a Ukrainian flag and replace it with a Russian flag in front of the Donetsk Oblast Regional State Administration building in Ukraine. Photo: courtesy of Andrew Butko.