Talabani's announcement on Thursday, made during a visit to Baghdad by British Foreign Secretary Jack Straw, marks a success for Sunni Arabs, who threatened to pull out of the political process if they were not given a bigger say on the committee.
"We have decided to add about 20 to 25 members from Sunnis in the committee, which will draft the constitution with full rights like other members who were elected by the parliament," Talabani said.
"This will be done very soon, and we are discussing to finalise the making of this decision," he added.
Talabani's call seemed to meet demands made a day earlier by top Sunni leaders for 27 seats on a committee drafting the new constitution.
Sunnis demanded a greater say
in the political process
It was unclear whether Talabani's announcement meant any new Sunni Arab members would have the same voting rights as the original 55 lawmakers who were selected to the parliamentary constitutional-drafting committee.
Two Sunni Arab lawmakers sit on a 55-member parliamentary committee drafting the charter, but Sunni Arabs said this was too small a representation.
The Shia-led government offered 13 additional places for Sunni Arabs from outside the parliament to help the 55-member committee draw up the constitution.
No voting rights were offered to the 13, but the committee said it would make all decisions by consensus.
But on Wednesday, Iraq's largest Sunni Arab organisations, the Iraqi Islamic Party and the Sunni Endowment, had rejected the offer of 13 and instead called for 25 seats with the same voting rights as the 55 lawmakers.
If they did not get their way, the Sunni groups threatened to boycott the political process.
Also unclear from Talabani's remarks was whether the new Sunni members would sit on a separate panel or join the original committee of 55.
"We have decided to add about 20 to 25 members from Sunnis in the committee, which will draft the constitution with full rights like other members who were elected by the parliament"
Since the 25 representatives will not be elected legislators, the Sunnis normally would have no voting rights on the constitutional panel.
A separate committee would have to be created to include them.
The draft charter will collapse if three of Iraq's four predominantly Sunni Arab provinces vote against it in a referendum this year.
The constitution must be drafted by mid-August and approved two months later in a referendum.
Sunni Arab approval is needed for the charter to take effect and new elections to be held in December.
Straw said Iraqi Prime Minister Ibrahim al-Jaafari's administration and the newly elected 275-member parliament "made a lot of efforts to pull Sunni representatives into government".
Straw also called on Europe to put aside its divisions over the US-led invasion of Iraq and help the country build a democratic future.
Straw (R) called on Europe to help
in the reconstruction of Iraq
"Yes, the Iraq war did divide Europe," Straw said after meeting Talabani.
"Now there is a new spirit around to put the past behind us to work for this new future for Iraq," he added.
Straw was in Baghdad for the EU's first high-level visit since the US-led invasion toppled Saddam Hussein's government two years ago.
The EU delegation included its foreign policy chief, Javier Solana, External Relations Commissioner Benita Ferrero-Waldner and Luxembourg's Foreign Minister Jean Asselborn.
Talabani, a Kurd, said it was time for Iraq and the 25-member EU to forge ahead with helping the war-torn country rebuild.
More than 80 countries and international organisations have been invited to a one-day session on 22 June in Brussels.
Top representatives from the United Nations, the Arab League and Iraq's neighbours, including Iran and Syria, are to attend the conference, which will aim to bolster international support for political and economic reforms and back efforts to draft a constitution.