US President Donald Trump was met with loud, sustained boos and chants of "Lock him up" from baseball fans at Nationals Park, Washington, DC, when he was shown on the in-stadium video screen just hours after he announced the death of Islamic State leader Abu Bakr al-Baghdadi.

Key points: Mr Trump was attending his first major league game since he took office

Mr Trump was attending his first major league game since he took office Pro-Trump crowds are known to chant "Lock her up" about Hillary Clinton at the president's campaign rallies

Pro-Trump crowds are known to chant "Lock her up" about Hillary Clinton at the president's campaign rallies Mr Trump's staff has long tried to shield him from events where he might be loudly booed or heckled, and he has rarely ventured into the neighbourhoods of the heavily Democratic city

Mr Trump attended the Houston Astros-Washington Nationals game with five wounded veterans and First Lady Melania Trump.

The boos ended only after the video screen cut to a shot of US service members waving to the crowd and then showed a message thanking the military.

As Nationals starter Joe Ross took the mound to warm up for the fourth inning, fans started chanting "lock him up" in an apparent reference to ongoing impeachment proceedings against the President.

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Pro-Trump crowds have frequently chanted "Lock her up" about Hillary Clinton at the President's campaign rallies.

Mr Trump was attending his first major league game since he took office in January 2017.

He did not throw out the ceremonial first pitch and arrived with no fanfare just as the game began.

Mr Trump, who campaigned on a promise to "drain the swamp," is deeply unpopular in the Washington area.

He received 4 per cent of the vote in the District of Columbia and lost both Maryland and Virginia in 2016.

Mr Trump's staff has long tried to shield him from events where he might be loudly booed or heckled, and he has rarely ventured into the neighbourhoods of the heavily Democratic city.

Mr Trump and the First Lady entered a lower-tier box to the left of home plate.

His presence was not formally announced, but fans in the section just below Mr Trump's suite turned to look toward the box as he arrived.

Some waved at the president as he smiled and gave a thumbs-up.

A dozen or so members of Congress accompanied the President, according to a list provided by the White House, including Senator Lindsey Graham of South Carolina and David Perdue of Georgia.

AP