Swimmers in Sliema had their early-morning swim ruined on Thursday after large patches of foamy sea slime emerged along the coast. 

Readers told Times of Malta that the slimy substance appeared at around 7.30am and was still there at around 10am, when reporters visited the area. 

Sea slime has started appearing along the coasts in recent weeks, with swimmers eager to enjoy the last few weeks of summer fearing that promises by fish farm operators were not being met.

The issue had plagued beaches in recent years, prompting the fish farm operator's lobby to commit to a series of self-regulatory measures to run during the summer months. 

Following Monday's report, the Environment and Resources Authority (ERA) responded by insisting that the fish farms were all inspected at least three times a week and were in line with all conditions. 

When contacted about Thursday's reports of slime in the sea, an ERA spokeswoman said officials went on site in the morning and "confirmed that the material in question was actually sea foam not slime generated from fish farms".

"It was actually generated by wind and sea currents and is a naturally occurring phenomenon, which normally occurs at this time of year,” she said.

"The foam has drifted ashore along the Sliema and St Julian's coast and is accompanied by dust and plant debris," she added.

Foam patches of what swimmers claimed were oily substances, similar to those  in Sliema on Thursday, have also been spotted in St Paul’s Bay, Marsascala and Buġibba in recent weeks.

In some cases, boat owners have also complained the slime was sticking to their vessels, sparking concerns this could result in long-term damage.

In a statement on Thursday, the Federation of Maltese Aquaculture Producers said the yellowish-white patches observed around the Sliema Exiles area "are in no case slime originating from fish farms and are most likely a natural sea foam phenomenon commonly observed following the first episode of rain following summer".