A warning has been issued after harmful algae was detected in a lake at a Stoke-on-Trent park.

Officials from Stoke-on-Trent City Council confirmed blue-green algae has been detected in the lake at Hanley Park after it began to turn green earlier this month.

The blue-green algae, technically known as cyanobacteria, is a collection of microscopic organisms can become abundant in warm, shallow, nutrient-rich waters. Blooms can form, which discolour the water or produce floating mats or scums on the water's surface.

It can be harmful to both people and pets. It can cause skin rashes and serious illness if it is swallowed.

Part of the lake at Hanley Park over the weekend. (Nub News)

Park users have been warned to keep dogs on leads and to avoid contact with the water.

The council says it is now treating the issue.

Stoke-on-Trent City Council said: "We've detected blue-green algae in the lake at Hanley Park.

"This can be harmful to both people and pets - it may cause skin rashes and serious illness if swallowed.

"Please keep dogs on leads and avoid contact with the water while we treat the issue."