KUALA LUMPUR -- An expanded Bangsamoro Transition Commission (BTC) will submit to Congress within a year a draft law creating a new autonomous government in Mindanao, government and rebel negotiators agreed here Sunday.

The BTC will now have 21 members, 11 to be nominated by the Moro Islamic Liberation Front and 10 by the government, according to a joint statement by both panels.

Under a peace deal signed in 2014, the BTC was to have 15 members.

Slots from the government side will be reserved for representatives of other groups that will be affected by the establishment of a new Bangsamoro.

Among them is the Moro National Liberation Front (MNLF), which signed its own peace agreement with the government in 1996.

"One of the ways in which we can be very inclusive is to increase the number of the members of the (BTC)," said Irene Santiago, who heads the government panel overseeing the implementation of the 2014 peace accord with the biggest Moro rebel group in the country.

Mohagher Iqbal, who heads the MILF side, said it was "more or less a difficult situation" when his group agreed to expand the membership of the commission.

"But in the spirit of improvement and enhancement, it's not a violation of that agreement, so we agreed," he told reporters.

Iqbal headed the BTC, which produced the proposed Bangsamoro Basic Law that ran into several roadblocks in the previous Congress. He said he would likely not chair the expanded commission anymore.

"I have done my part and we have delivered and I think on my part, personally, it's already a fulfilling thing for me," he said.

The new draft will be submitted to a Congress where one half is controlled by a "super majority" allied with President Rodrigo Duterte.