Mystery surrounds sheets of grey dust which settled on cars and homes across Coventry and Warwickshire and beyond at the weekend.

The Environment Agency has sent samples of the unexplained substance to the lab after ruling out the Cemex plant in Rugby as a potential cause.

More than 80 people from as far a field as Solihull, Lichfield, and Nottingham called the agency to complain about the grimy film.

Though experts were sent out to the Cemex plant on Sunday the agency's environment manager, David Hudson, believed it must have come from another source.

He urged people to be vigilant and to report any other similar occurrences.

Anyone affected should call the agency's 24 hour hotline on 0800 80 70 60 or visit Environment Agency site.