A thick white blanket settled gently on the seaside town of Cleveleys near Blackpool on Wednesday, but this was no seasonal dusting of snow from above.

The Environment Agency dispatched officers to Princess Promenade to gather evidence as gobs of foam blew in from the sea and smothered streets, cars and houses.

The foam is whipped up by strong winds once or twice a year along the town's seafront and vanishes soon after, a spokeswoman for the agency told the Guardian.

Lab tests on samples collected in earlier years have found no signs of pollution. Decomposing algal matter is the prime suspect for the mysterious lather.

"It appears to be naturally occurring. When the tides and winds combine to churn dead algal matter up from the bottom of the sea, it produces this foam, which is quite dramatic," the spokeswoman said.

Officers visited Cleveleys on Wednesday and again on Thursday to collect more specimens to analyse. The results of the tests are expected to confirm the foam is natural and not caused by detergent in seawater or other pollution.

By studying the foam, the agency hopes to learn how and why it forms and so predict when the froth will return.

"If we can understand what conditions cause it, that will help us predict it and help local authorities involved in the cleanup operations," the spokeswoman said.