US President Donald Trump says his top economic adviser Larry Kudlow has had a heart attack and is now in hospital.

He tweeted the news shortly before his widely-anticipated meeting with North Korean leader Kim Jong-Un in Singapore.

Mr Kudlow accompanied the US president to last weekend's G7 summit in Canada that ended in disarray, with President Trump retracting his endorsement of a joint statement.

Mr Kudlow joined the Trump administration earlier this year.

"Our Great Larry Kudlow, who has been working so hard on trade and the economy, has just suffered a heart attack. He is now in Walter Reed Medical Center," President Trump wrote on Twitter.

Mr Kudlow's wife, Judith, told the Washington Post that her husband was "doing fine".

Mr Kudlow, previously a television commentator, has taken a tough stance on trade.

The US imposed tariffs on steel and aluminium imports from the EU, Canada and Mexico on 1 June, setting the scene for a tense G7 meeting hosted by Canadian Prime Minister Justin Trudeau over the weekend.

The summit ended with Mr Trudeau vowing to press ahead with retaliatory tariffs and Mr Trump lashing out at his host.

Mr Kudlow has defended the new tariffs and said his boss should not be blamed for trade tensions.

After the summit, Mr Kudlow told CNN that the president and his team had gone to the summit "in good faith" but that Mr Trudeau had "stabbed us in the back."