A recent increase in cancelled bus services across the Wellington region has been blamed on drivers using up sick leave before their contracts expire. (File photo)

Bus drivers using up sick leave before their contracts end later this year is believed to be contributing to a recent increase in cancelled bus services across the Wellington region.

Greater Wellington Regional Council said last week that up to 20 services a day were being cancelled across the Metlink network due to "unexpected absences" among drivers.

An average day usually sees about five to seven services cancelled.

SUPPLIED Up to 20 bus services a day are being cancelled due to a lack of drivers.

Drivers' contracts will end in June or July. The Tramways Union, which represents them, is refusing to accept new contracts being offered by incoming operator Tranzit because of a disagreement over employee terms and conditions.

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﻿It is understood some healthy drivers are now taking sick leave, which will not be paid out to them, before their contracts run out.

ROBERT KITCHIN/STUFF Wellington bus drivers' current contracts will expire in June or July, after which, new operator Tranzit will take over many of Wellington's routes in its new bright green and blue buses.

Tramways Union secretary Kevin O'Sullivan said he was not aware of "excessive" sick leave being taken. But if it was, the regional council was to blame.

"If it is happening, I'd suggest it's because of the undue stress the regional council have caused these people by the way in which they've gone about destroying a very good public transport system," he said.

"If people are taking sick leave then I'd suggest that's why. I'd be surprised if there was a large number of people calling in sick for just no reason. A lot of them are very distressed about what's happening."

MONIQUE FORD/STUFF An average day usually sees about five to seven services cancelled.

Masterton-based Tranzit will operate 60 per cent of the region's bus services from July.

The company and the union have been in disagreement over the new contracts for some time, and the union is threatening widespread industrial action if the dispute is not settled, which would cause "chaos" across Wellington.

O'Sullivan reiterated that threat on Tuesday.

"They're saying there are 15 trips a day cancelled now. Well in June [and] July, 1500 trips are going to be missing."

Some drivers were planning to take up jobs in Australia rather than accept new contracts here, while a large number of drivers of Samoan descent planned to head back home and retire, O'Sullivan said.

The new contracts will take effect in the Hutt Valley in June, and in Wellington and Porirua in July.

The union says the contracts will result in lower pay for drivers because of the loss of penal rates, including double-time on Sundays, time-and-a-half on Saturdays and an increased rate for longer days.

Tranzit says drivers will be better off under its new contracts, with hourly rates to increase from between $18.65 and $19.35 under current operator NZ Bus, to $22 an hour under Tranzit.

Newlands Coach Services chief executive Ian Turner did not return calls on Tuesday, while NZ Bus, which is set to lose the majority of its contracts from July, is continuing to ignore media queries.

Turner did say last week that services were being cancelled "due to shortage of staff, and sickness".

A regional council spokesman said the organisation could not comment on matters such as sick leave because it did not employ drivers.

The spokesman acknowledged a driver shortage was impacting on bus services and apologised to affected commuters.

The new contracts would provide a more connected and efficient public transport network which would take people to more places, he said.