Update, 12.10pm: State Highway 27 in Matamata has now reopened.

Following an earlier truck fire south of Matamata, near Taihoa South Rd, diversions have now been removed and SH27 is open in this area.

The truck trailer carrying heavy machinery caught fire, blocking the road for most of the morning.

Earlier, 6.58am:

People travelling from Tauranga to Matamata are being warned to expect delays.

Police are reporting a truck trailer carrying heavy machinery is ablaze on State Highway 27 in Matamata, blocking the road.

"The north and south bound lanes are currently closed, and vehicles are being diverted.

"Motorists, especially truck drivers, are advised there will be delays and to avoid the area."