Obama pessimistic about global economy after Brexit

US President Barack Obama says he has long-term concerns about global growth.

US President Barack Obama. Picture: AFP.

LONDON - United States (US) President Barack Obama has painted a pessimistic picture of the global economy following the United Kingdom's (UK) vote to leave Europe.

Obama says he has long-term concerns about global growth.

The US president famously intervened in the Brexit debate prior to the vote, pleading for the UK to remain in the EU in an appeal which many believed backfired.

He now says the decision would freeze the possibilities of investment in Great Britain and Europe as a whole.

Speaking at a summit in Canada, he said the global growth rates were already weak.

He adds, however, that the economy would hold steady in the short term.

He has strongly defended free trade and promised to press on with plans for a Trans-Pacific Partnership.

This comes as former London mayor Boris Johnson announced that he will not run for prime minister, following David Cameron's decision to step down.

Johnson wrapped up a speech a short while ago, but refused to take questions on his decision.