Seven Irish ministers and the ex-prime minister Bertie Ahern have all been targeted by envelopes sent to the Irish parliament which contained white flake-like substances.

A full scale Irish police investigation has been launched after the envelopes, which contained hand-written note stating "Have a Happy Christmas," came to light. Some of the envelopes warned the ministers to "beware."

Irish ministers who received the letters included transport minister Noel Dempsey, health minister Mary Harney and tourism minister Mary Hanafin.

Police were also called in to investigate unrelated death threats made against former prime minister Ahern at his constituency office in Dublin.

A Dublin firefighter was arrested after police traced three voicemails in which threats were made on Ahern's life to his phone.

It is unlikely that the man will be charged however as the former prime minister opted not to make a statement.

In most cases the envelopes containing unidentified substances were opened by ministerial staff. Following detailed analysis however, the substance in the envelopes turned out to be flour and was ruled totally harmless.

Police told the press that nonetheless it was still an unnerving experience for all involved and it was clearly a crude attempt to intimidate.