The train workers' union is poised to pull its members from operating asbestos-contaminated locomotives, making it ''very difficult'' to move freight around New Zealand.
KiwiRail bought 40 DL locomotives from China within the last four years.
On Friday, after asbestos was discovered, they were removed from service and quarantined for testing.
Rail and Maritime Transport Union general secretary Wayne Butson said this morning he understood tests from four of the locomotives were back from the lab, but KiwiRail had not revealed the test results to the union.
In any case, they were airborne tests and the union believed tests - where a cloth was run along a surface inside the locomotive then tested for asbestos - were more telling about whether asbestos was present.
He understood these tests had not yet come back.
He called on KiwiRail to maintain its quarantine of the trains until all asbestos had been cleared from the locomotives.
If it did not do this, the union - which has a membership rate of more than 90 per cent - would tell its members not to operate them, effectively meaning they could not run.
''It's going to make life very, very difficult for rail and I really feel sorry for the customers of KiwiRail,'' Mr Butson said.
KiwiRail still had other locomotives, meaning some freight could still be moved without use of the Chinese locomotives, he said.
While the quarantine had come at a fortunate time - when less milk was being transported, Solid Energy was moving less coal, and Tauranga's port was quiet - the sidelined locomotives could have a ''significant impact'' on freight if the asbestos was not cleared rapidly.
Clearing the asbestos, especially from locomotive cabs, would be a major operation.
Some services had already been cancelled, he said.
Over the past few years, numerous workers had spotted asbestos in the locomotives but KiwiRail had reassured the union there was none.
The union would only let its members back on the locomotives if lab tests showed there was no asbestos present. But given asbestos had long been suspected, and now found, this was extremely unlikely, Mr Butson said.
''If they have lied to us in the past, how do we know they are not lying to us now?''
KiwiRail could not comment on Mr Butson's claims before this afternoon.
- The Dominion Post
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