A bare-faced bank robber stood in line behind other customers before holding up a teller and making off with cash.

The man walked into the BNZ in Tawa's Oxford St about 3.30pm yesterday, wearing a distinctive pair of yellow waterproof pants.

Detective Senior Sergeant Mike Oxnam said the young man patiently waited in line behind other customers, then once at the head of the queue, told the woman teller he was armed before demanding money.

The teller remained clear-headed, handing over cash, and the man quickly left the building. Nobody was hurt and though there were five customers in the bank, only one noticed what was happening, Mr Oxnam said.

The robber was possibly a light-skinned Maori, in his late teens or early 20s, and was wearing a black cap, and a black hooded sweatshirt with red writing on it. He was last seen heading south down Oxford St.

Given the fact that he did not try to mask his face, Mr Oxnam questioned his experience as a bank robber. Police said he may be armed and should not be approached.

Anyone who recognises the man should contact Porirua police urgently on (04) 238-1401.