Ukraine fighter jet near MH17 before crash: Moscow

Moscow also denied supplying Ukrainian separatists with Buk missile systems or any other weapons as it sought to head off international accusations it was responsible for the downing of the Malaysian plane with 298 people on board.

In the early hours of Monday, the Kremlin released a video address in which a grim-faced President Vladimir Putin said the tragedy should unite and not divide people.

Armed with a number of slides, charts and images, two high-ranking officials of Russia's General Staff later Monday laid out a case against Kiev and Washington at a specially called briefing.

Lieutenant-General Andrei Kartopolov said the Malaysian plane strayed north of its planned route, adding that a Ukrainian SU-25 fighter jet, which is typically equipped with air-to-air missiles, had been recorded in the proximity of the Boeing 777.

The Malaysian plane "deviated from its route to the North ... The maximum deviation was 14 kilometres," he said.

"An altitude gain was recorded for a Ukrainian armed forces plane," he told the briefing. "Its distance from the Malaysian Boeing was three to five kilometres (two to three miles)," he said, noting that the SU-25 is capable of reaching a height of 10,000 metres "for a brief time."

"With what aim was a military plane flying along a civilian aviation route practically at the same time and at the same flight level as a passenger liner?" said Kartopolov. "We would like to receive an answer to this question."

The Russian official also challenged Washington to release its satellite images to back up its claim that rebels targeted the Boeing 777 with a missile.

"No one has seen those images," Kartopolov said, noting that a US satellite flew over the rebel-held part of Ukraine at around the time the plane crashed.

"Whether it is a coincidence or not, but the time of the disaster and the time of monitoring by the US satellite dovetail."

Kartopolov also said that the Russian defence ministry detected activity from radar stations that are used to operate missile systems on the day of the tragedy.

"From July 17 (Thursday) the intensity of the operation of Ukrainian radar stations increased to the maximum," said Kartopolov.

He added seven radar stations were operating close to the area of the disaster on Tuesday, eight on Wednesday and nine on the day of the crash, Thursday.

After the crash, just four radar stations were operating in the area on Friday and just two on Saturday, he added.

Kartopolov insisted Russia had not supplied Ukrainian separatists with Buk missile systems or any other weapons.

"I want to stress that Russia did not give the rebels Buk missile systems or any other kinds of weapons or military hardware," he told reporters.

He dismissed images allegedly showing Buk systems being transferred from Russia into Ukraine as fake, claiming Ukraine's missile systems had been moved close to the scene of the disaster ahead of the crash.