The United Arab Emirates and Bahrain have warned citizens travelling in the United States to be careful around protests following recent police shootings of black men.

A "special alert" issued by the UAE embassy to Washington, DC, on Saturday urged citizens to stay away from demonstrations in US cities.

State news agency WAM said the warning followed a protest by supporters of the "Black Lives Matter" movement in Washington on Friday.

The island kingdom of Bahrain also issued its own advisory on Twitter, telling nationals to be "cautious of protests or crowded areas".

The US State Department routinely issues travel advice for Americans abroad.

On Friday, the Bahamas put out its own advisory about US travel, saying young men especially should "exercise extreme caution in affected cities in their interactions with the police".

Demonstrations across the US continued into the early hours of Sunday, five days after Alton Sterling - a 37-year-old black man and father of five - was killed by white police in Baton Rouge, Louisiana.

His death was followed by the police killing in Minnesota of Philando Castile, a young, black man who worked at a local school serving food to children.