The trustee administering $541 million in bonds from Suntech Power Holdings Co sent the solar company a notice of default on Saturday as the deadline to redeem the notes passed, a person familiar with the matter said.

The move allows bondholders to sue the Chinese company in US courts, according to the person, who asked not to be named because the information hasn't become public. A default would be the first by a Chinese mainland company. Suntech said holders of 63 percent of the bonds agreed to delay exercising their rights for two months until May 15.

"We believe it is in the best interests of all of our bondholders to come to a consensual restructuring and encourage bondholders that are not signatory to the agreement to join this process," Suntech said in a statement released by its public relations adviser, Weber Shandwick in Shanghai.