Lyttelton Port workers will strike as of midnight tonight.
A last ditch effort of mediation between the Rail and Maritime Union and Lyttelton Port Company has failed.
Union organiser John Kerr says LPC refuses to pay between 50 and 75 workers for the days they were 'illegally locked out' and unable to work last week.
The Port maintains the union didn't give enough notice - and all international shipping arrangements were made and required seven days to turn around.
The union also bargained for a salary increase - but there's still a one per cent difference between them and what their other maritime union colleagues have been offered.
Mr Kerr says that's not good enough.
"The difficulty is that it would mean our members literally working alongside people who get paid more than them, doing the same job."
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