Storm erupts over secret tyre test for Mercedes

A storm has erupted in the Monaco paddock about an until-now secret Pirelli tyre test involving Mercedes.

British F1 broadcasters Sky and the BBC revealed on Sunday morning that Lewis Hamilton and Nico Rosberg were both involved in a multiple-day, 1000km tyre test between the Spanish and Monaco grands prix.

The BBC said Red Bull and Ferrari are furious, and "considering a protest" due to the ban on in-season testing.

But the report also said sources confirmed the FIA was aware of the test, which is allowed on the grounds of needing to safety-test planned changes for Canada next month, and 2014.

"Some teams have reacted badly," 1996 world champion Damon Hill told Sky, "(but) I have spoken to Niki Lauda and he assures me that they have okayed it with the FIA and the reason it is ok is because the safety regulations overrule the sporting regulations.

"If there is a safety issue, which seems to be the insinuation, then somebody has to do the testing. It just looks like Mercedes might have got in there first," he added.