Zurich American Insurance and Employers Insurance of Wausau have agreed to fulfil their World Trade Centre (WTC) claims payment obligations, saying the modified rebuilding plans for the site will not affect claims costings.

The insurers are the first of the original seven to relinquish their position that the modified designs would adversely affect insurance payments after the towers collapsed on September 11 2001.

The withholding of payments has slowed rebuilding on the site. Unless the remaining five insurers join Zurich and Wausau, construction will continue to be stalled.

Zurich will provide $US53 million ($69 million) of the WTC rebuilding funds while Wausau will provide $US62.9 million ($81.9 million). The total claims amount to more than $US3.55 billion ($4.63 billion).