NEW ZEALAND OPEN: Additional security is being arranged for this week's New Zealand Open featuring Tiger Woods after the US embassy received a cyanide-laced letter threatening the eventt, police said yesterday.

Tunnels and bridges to the golf course will be guarded around the clock and police will patrol trains after transportation was referred to as a possible target in the letter.

A letter containing cyanide and threats against the Open and Israeli nationals was received by the US embassy in Wellington last month.

More than 150 police, including a 30-strong special search unit, were already at the course yesterday checking facilities.

Woods, the tournament's biggest drawcard, is due to arrive today.

Speaking on Sunday from Hawaii after the Mercedes Championship Woods said the threats would not deter him from going to New Zealand.

"I know the tournament officials have done a wonderful job of organising the event. They've assured me I'm going to be safe."