Workers employed by Lyttelton Port Company protesting outside the offices of the Christchurch City Council holding company.

Port workers have put off strike action at Lyttelton until next Tuesday and negotiations are under way again, much to the relief of importers and manufacturers disrupted by shipping delays.

The Rail and Maritime Transport Union initially offered to lift strike action for Thursday and Friday and then extended it until March 20 after a request from port operations manager Paul Monk.

He acknowledged the initial "gesture of goodwill", and the longer period needed to arrange for normal shipping.

JOSEPH JOHNSON/STUFF Lyttelton Port workers protesting in central Christchurch.

Workers would be paid even if there was little work until regular shipping resumed, Monk said.

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At midday about 150 Rail and Maritime Transport Union members also picketed the offices of council-owned Christchurch City Holdings, the parent company of Lyttelton Port.

JOSEPH JOHNSON/STUFF Lyttelton Port workers Polly Bysterveld and Laurie Collins protested outside the offices of the Christchurch City Council's holding company.

Vehicle and machinery importers ​have been most affected by shipping disruption because ships were already delayed last month for fumigation after stink bugs were found in cars from Japan.

"It has a flow on effect on other businesses as well as our customers who have pre-purchased vehicles online or from our car yard which is half empty at the moment," Andre Hopman of Hopmans QE11 said.

"I've got 30 Nissan Leaf electric cars coming and a total of 110 cars on the water. I've got 25 cars pre-sold for customers who need them before the end of the financial year," Hopman said.

JOSEPH JOHNSON/STUFF Mark, Ngahuia and Willem, walk away after they joined other families and workers employed by Lyttelton Port Company.

Nick Owens, owner of Auto Inspection Services which certifies imported vehicles and machinery, said there were four other businesses of a similar size in Christchurch affected.

"It extends to suppliers, panelbeaters, groomers. I've already had about two weeks without any work for my 12 staff who have been really helpful by taking leave," Owens said.

Manufacturers Association chief executive Dieter Adam said some manufacturers were using road and rail services through Timaru port, lifting costs dramatically.

CHRIS HUTCHING/STUFF Vehicle and machinery importers have been most affected by shipping delays.

Meanwhile, Christchurch City Holdings chairman Jeremy Smith accepted a letter from Rail and Maritime Transport Union organiser John Kerr asking for the CCHL board's intervention in the interests of the Canterbury region. But Smith refused to become involved.

Union member Polly Bysterveld said the industrial action was about safety more than just the money.

Another worker Laurie Collins said the main issues were rosters, and obtaining the same pay agreement as Maritime Union members who had a 4 per cent increase, rather than the 3 per cent offered to Rail and Maritime Transport Union members.

Collins said the rolling eight hour rosters meant straddle crane drivers could be ordered to work a 7am to 3pm shift, and return to work at 11pm the same day to work through the night until 7am.

About one third of the handling staff were in a permanent relieving pool and therefore couldn't afford to pass up the work when it was offered.

Qualification requirements for drivers had also been lowered, adding to safety concerns, Collins said.

He also asked where chief executive Peter Davie was.

Operations manager Monk said Davie continued to be fully involved in directing negotiations with the union.

"He remains overseas on port business, while being constantly in contact and fully across the industrial action situation and is leading our efforts to resolve the dispute," Monk said.