A bomb placed in a vehicle exploded outside the British embassy in Bahrain's capital early on Sunday, the interior ministry said.

There were no casualties in the blast, the ministry and a British embassy spokesman said.  

'Given the strength of the explosion and the debris it scattered, it was a highly-explosive substance that was used,' a ministry spokesman said in comments on Twitter posted live from a news conference. 'The explosion was the result of a package placed under the front tyre.' 

'There were no casualties or damage to the embassy. We cannot identify yet the cause or the responsibility,' an embassy official said.

'We are working with the Interior Ministry and we have requested a temporary increase in security.' - Reuters