Image copyright AP Image caption Mr Obama sampled the city's filtered tap water

President Barack Obama has sipped a glass of filtered water on a visit to the Michigan city of Flint, which has been wracked by a public health crisis.

He took a drink of the city's filtered water to "show it was safe".

The visit was prompted by a letter the president received from eight-year-old resident Amariyanna Copeny.

A change in water supplier in 2014 sparked the crisis, with nearly 100,000 people exposed to high levels of lead, sparking an outcry.

Mr Obama declared a state of emergency for the city in January and ordered federal aid for the crisis.

"Filtered water is safe, and it works," he said during a discussion with officials in Flint.

"Working with the state and the city, filters are now available for everyone in the city."

Image copyright EPA Image caption Protesters have demanded the firing of Governor Rick Snyder

More than 40% of Flint residents are impoverished and more than half are black.

Residents must use faucet filters or bottled water as a result of the crisis.

Michigan Governor Rick Snyder has been criticised for his handling of it and two state employees in the environmental department have been charged with misleading the US government about the problem.

And a Flint employee is being charged with altering water test results.

Media playback is unsupported on your device Media caption Flint resident Melissa Mays: 'Our hair fell out'

Mr Snyder was booed at a high school where Mr Obama later addressed hundreds of people.

"I understand why you are angry and frustrated. I want to come here today to apologise," Mr Obama said.

Protesters gathering near the school are chanting "Flint lives matter", arguing that state officials' response to the water situation was not enough.

The Michigan Senate approved $128m (£88m) in aid for Flint on Wednesday.

Some of that money will go towards replacing lead pipes connecting water to customers.