Updated 1.45pm with Splash and Fun comments

Black effluent oozing down the rocks at the popular swimming cove at Bahar ic-Caghaq has disgusted swimmers, a few of whom have sent in photos taken over the past few days.

The slime was reported to the Environmental Resources Authority on Monday, who acknowledged the report but so far no explanation has been forthcoming.

Similarly dark slime was also reported in parts of St Paul's Bay last month, with the town's mayor Graziella Galea having highlighted the problem on Facebook. 

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Parts of St Paul's Bay were also plagued by the mystery slime last month, as this photo posted to Facebook by the town's mayor shows.

 Splash and Fun take responsibility for one of the two trails

Splash and Fun director Patrick Vella confirmed that there were two separate trails - one of which is considerably darker than the other. He said that the lighter one was indeed chlorinated water leaking from one of the pools at the complex.

"We did work on this in winter and thought that we had solved it, but clearly there is still a problem. We are aware of this and will be working on it as soon as the season is over," he said.

Mr Vella confirmed to the Times of Malta that both the ERA and the Health Department sent people to investigate the other leak this morning.