Donald Trump appeared to shove Montenegro's Prime Minister out of the way in a bid to get to the front of a group of Nato leaders - a moment which was captured on film.

The US President was walking with other world leaders at when he seemed to forcibly push aside Dusko Markovic.

The incident was captured on film on the first day of a key summit at the alliance's headquarters in Brussels.

However, it was not the first awkward encounter of the day for the Republican leader.

Just hours earlier, he was pictured in an unrelenting handshake with newly-elected French President Emmanuel Macron.

The two locked hands for so long that both leaders' knuckles were described as turning white with their faces reportedly tightening.

Mr Trump later delivered a blunt message to European Nato members that they must spend more on defence to meet the threat from terrorism.

He said many countries owed "massive amounts" for failing to meet the military alliance's target to spend 2 per cent of GDP on defence.

In the wake of the "barbaric" Manchester bombing, Mr Trump said two per cent was a "bare minimum" which should be increased to allow Nato to "stop terrorism in its tracks".

There were signs of apparent disgruntlement among the European leaders lined up to hear Mr Trump's speech, which followed a moment of silence in honour of the victims of the Manchester attack.

French President Emmanuel Macron, Luxembourg's Prime Minister Xavier Bettel and Belgian PM Charles Michel were seen to whisper among themselves as Mr Trump took countries such as theirs to task for past underspending.