The country's largest listed company, Fletcher Building is marshalling its staff and providing building materials to assist with the response to Tuesday's powerful earthquake.
The company says 200 engineers, supervisors and other staff, are available to help immediately and is determining how many staff in other areas are available to assist.
Fletcher Building's general manager of investor relations Philip King says the PlaceMakers store in Riccarton is open to provide building materials to aid rescue teams.
Infrastructure consultancy firm Opus International Consultants is sending a contingent of engineers and specialists to help its staff in Christchurch and assist in the recovery.
Opus managing director, David Prentice, says the company has 250 staff in Christchurch and all have been accounted for.
Christchurch sites assessed
The Port of Lyttelton says it needs to carry out urgent minor repair work to its container operations, and it could take 10 days until normal operations resume.
It aims to have the container operations running on a limited basis, in three to four days.
The port says its oil berth operation has held up well, but it is checking the pipework, and expects it to be operating again before a tanker arrives to to discharge fuel on Saturday.
Navy divers have been helping its engineers to assess port structures and carry out a series of soundings to review the channel depth, the port says.
Solid Energy says its mining operations are continuing to operate as normal, and coal destined for foreign customers is being stockpiled at its mines.
The West Coast coal rail route and Lyttelton Port are closed, as KiwiRail and the port check their facilities.
Solid Energy says it expects to issue force majeure notices for the interruptions to shipments.
Steel and Tube is assessing its Christchurch operations, and its branches will remain closed for at least a couple of days. The company says there are no reported injuries among its 120 staff.
Scott Technology is working to make sure its buildings are structurally sound and machinery is safe to operate.
The company says the timing and extent of a return to operation will depend on the results of structural checks and on access to services.
Skellerup is still evaluating the effect of the earthquake on its facilities. The company says it has established supply lines that will ensure that Skellerup continues to meet demand from its customers.
The commercial property landlord, The National Property Trust, says Eastgate Shopping Centre has been damaged, and may need to be closed for an extended period. General manager John Crone says the centre has full insurance cover.
Sky City Entertainment says some staff and customers were treated for minor injuries after being evacuated from the Christchurch Casino. The casino remains within the emergency cordon, but appears to have escaped any major damage, though it will remain closed for several days until a structural inspection is possible.
Meridian Energy says it may set up a temporary call centre in Wellington, after its Christchurch building was damaged in the earthquake.
The publicly-owned energy company says all 80 staff escaped, but the building, which houses its national call centre, billing and back-office operations, has been damaged, and remains off-limits within the inner city cordon.
PGG Wrightson says its buildings, distribution centre and stores in Christchurch have not been damaged.
It says all operations are open for business, with the exception of the Rangiora and Blenheim stores which remain closed today.