Ahmed Mujuthaba's resignation came after the opposition Maldivian Democratic Party (MDP) of ousted President Mohammed Nasheed yesterday passed a resolution, saying the party is temporarily withdrawing from the talks.
Mujuthaba said if any party involved in the process withdraws then there is no need for the all-party talks now been converted to leaders' dialogue.
They can continue the talks in the Parliament, he added.
The leaders dialogue held its first meeting at August 30 with the participation of President Mohamed Waheed.
In a statement, the MDP said that it has decided in its National Executive Council meeting to stop participating in the talks for the time being. But the statement did not give the reasons behind the decision.