Reuters - Britain has summoned the Iranian ambassador to the country to convey its strong objections to the brief arrest of London�s envoy to Tehran on Saturday, a spokesman for Prime Minister Boris Johnson said.

�This was an unacceptable breach of the Vienna Convention and it needs to be investigated,� the spokesman said on Monday. �We are seeking full assurances from the Iranian government that this will never happen again.

�The FCO has summoned the Iranian ambassador today to convey our strong objections.�

Reporting by Elizabeth Piper, writing by Kate Holton; editing by William Schomberg