A man claiming to be God threatened to blow up a Work and Income office.

On November 1 last year, Jason Adam Beckford made 21 abusive phone calls to Work and Income, during which he threatened to blow up the Lower Hutt office and gave his name as God.

In Blenheim District Court yesterday, the 44-year-old vineyard worker, of Riversdale in Marlborough, admitted a charge of misusing a telephone to give a fictitious message that he would blow up the office. He was remanded on bail to November 13 for sentencing.

Police prosecutor Sergeant Mark Lucas said when Beckford began making the series of abusive phone calls he used a number of false names, including Dave, David Williams, Andrew Graham, Graham Williams and God.

During the fourth call he became increasingly upset and told the call centre staff, "I will come to your office and blow it up".

A 17-year-old associate of Beckford was at the Work and Income office in Lower Hutt, which was identified as the target and was shut down for 45 minutes, he said.

When police called Beckford soon after and asked him to hand himself in, he refused and told them he would change the sim card on his phone, Mr Lucas said.

Police later found Beckford had moved to Blenheim and when spoken to he denied the offending.

Mr Lucas said extra security staff were called to the Lower Hutt office. For the rest of the day in question clients were required to present their identification before being allowed in.

The maximum penalty for the charge is three months' prison or a fine up to $2000.