Tianjin has extended the deadline for its biggest carbon producers to comply with the municipality's emissions trading scheme a second time, giving companies two more weeks to hand over permits to the government.

The 114 energy and industrial firms covered by the Tianjin market were supposed to hand over permits to cover for their 2013 emissions on Thursday.

But the deadline has been extended to July 25, the Tianjin Climate Exchange announced Tuesday, as the government needs more time to make final adjustments to permit allocations to companies whose 2013 emissions varied significantly from what had been expected.

Trading of 2014 permits will start on July 28, the exchange said.