Petrol prices in Tauranga have increased by five cents with 91 octane now $2.119 per litre at Caltex, BP and Z Energy.

Z Energy spokesperson Jonathan Hill says a brewing diplomatic crisis between Iran and western nations has put pressure on product prises.

He says there has been no sign of easing of pressure on margins.

'We were hoping that things would get better over the weekend, but if anything, they've got slightly worse.”

The diesel price is unchanged.