The Russian Defence Ministry has claimed that a Ukrainian warplane flew within 3-5km of the crashed Malaysia Airlines MH17 plane and has asked Kiev for an explanation.
The ministry said that it did not detect any missiles launched near the downed plane's flight path and asked the United States to share satellite images.
The ministry also said that Russia did not deliver any SA-11 Buk missile system or "any other weapons" to pro-Russian separatists in eastern Ukraine.
Within hours of the MH17 crashing into wheat fields in eastern Ukraine killing 295 passengers and crew on board, a tweeter by the name of 'Carlos' (@spainbuca) and claiming to be an air traffic controller based in Kiev, suggested the doomed flight had been shadowed by two Ukrainian air force jets.
He alleged that Ukrainian military personnel had stormed into the the air traffic control room and seized flight data records after the disaster and tried to tell the controllers what they had to say about the downing.
He also tweeted that there were "foreigners" who came in with the Ukrainian military when they locked down the ATC station.
'Carlos' has now deleted his Twitter account and has not replied to questions sent by email from IBTimes.co.uk.
However, a Ukrainian security source told Reuters that Kiev stands by the information that separatists received a Buk-M1 missile system from Russia.
The US also said that it detected a surface-to-air missile being fired from a rebel area in eastern Ukraine.
"We assess that Flight MH17 was likely downed by a SA-11 surface-to-air missile from separatist-controlled territory in eastern Ukraine," it said in a statement.
All 298 people on board the flight died when it crashed over separatist-held territory in eastern Ukraine.
The separatists have allowed Dutch investigators to examine the bodies from the crash site at a railway station in eastern Ukraine while heavy clashes have been reported in Donetsk, killing at least three civilians.
The Dutch Disaster Victims Identification team are the first international investigators allowed at the site of the Boeing 777's shooting down.
A passenger list revealed that the plane was carrying 193 Dutch nationals, 43 Malaysians, 27 Australians, 12 Indonesians, 10 Britons, four Germans, four Belgians, three Filipinos and one from Canada and New Zealand.
Ukrainian Prime Minister Arseniy Yatsenyuk has proposed that the Netherlands lead an international investigation into the crash while President Petro Poroshenko ordered government forces to not fire within 40km of the crash site.