Media playback is unsupported on your device Media caption David Cameron: "In the end Russia needs its engagement with the West"

Russia could face further sanctions unless it stops "destabilising" Ukraine, David Cameron has said.

Speaking at the G20 summit in Brisbane, Mr Cameron said there would "have to be a very different relationship" between Europe and Russia if "we continue to see Russian troops" inside Ukraine.

After making the comments, the UK PM met Russian President Vladimir Putin.

Russia has denied its troops are in Ukraine, but it has previously said Russian "volunteers" may be fighting.

Before the private discussion with Mr Cameron, Mr Putin said EU and US sanctions were a mistake, were against international law and would harm the global economy as well as Russia.

'Wrong direction'

Speaking to the BBC, Mr Cameron said: "What we need to see is Russia respecting the territorial integrity of Ukraine and the right of this country to choose its own future."

He said that could lead to a "good future" for Ukraine, and for relations between Europe, Britain and Russia.

"But if Russia continues to destabilise Ukraine and we continue to see Russian troops and Russian tanks inside Ukraine then there is going to have to be a very different relationship between Britain and Europe on one hand and Russia on the other, and the potential for further sanctions," he said.

Media playback is unsupported on your device Media caption What is the point of the G20 summit? In 90 seconds

After the meeting between the two leaders, a Kremlin spokesman said they both expressed an interest in rebuilding relations between the UK and Russia.

But Mr Cameron said Russia must "recognise that there's only one legitimate government in Ukraine" - and said Mr Putin's government was heading in the "other direction".

Pro-Russian separatists have been fighting Ukrainian government forces in the east of the country since April.

At least 4,000 people have died and about a million have fled their homes.

Russian warships

Ukraine and its Western allies have accused Russia of sending military forces into Ukraine, something the Kremlin denies.

The EU imposed sanctions when Russia annexed Crimea in March and has added further measures since, but on Tuesday German Chancellor Angela Merkel said no new sanctions were planned.

The Ukraine conflict is one of the issues being discussed at the G20 meeting of world leaders, at which Russia has faced criticism for sending a fleet of warships to the Australian coast at the same time as the summit.

Mr Cameron accused Mr Putin of "machismo" over the move.