The Syrian opposition said on Sunday it rejected any attempt by the regime to delay the next round of peace talks until after a parliamentary election on April 13 and urged Russia to press its ally into serious talks on a political transition.

The two sides have been holding separate talks for the past week in Geneva with U.N. Special Envoy Staffan de Mistura, who has said he plans to suspend them on Thursday and resume in early April.

"We're aware that the regime has asked for a two-week delay for the next round of talks. The regime is trying to evade its responsibilities and postpone negotiations," Yahya Qadamani, deputy coordinator of the opposition High Negotiations Committee (HNC), told a news conference in Geneva.

"We insist that the next round be held on time. The regime is not entitled to impose any postponement of the next round that begins on the April 4."

"We hope that Russia uses its influence on the Assad regime to enter into serious negotiations over a political transition," he said, making clear also that the political transition should end with the ousting of Assad.

Earlier, HNC spokesman, Salim Al-Muslat, told reporters in Geneva: "We won't accept a postponement to hold illegitimate elections."

The HNC had not been informed by de Mistura of any delay in the next round, but would raise it with him in talks resuming on Monday, he said.

Syrian regime negotiators at the talks are coming under unaccustomed pressure to discuss the fate of Assad, whose departure the opposition demands.

De Mistura describes Syria's political transition as "the mother of all issues" and after the latest week of talks, praised the opposition for the depth of their ideas, but criticized the veteran diplomats on the regime side for getting bogged down.

Riad Hijab, a former Syrian prime minister who leads the HNC delegation, is due in Geneva on Monday, HNC sources said.

PHOTO CAPTION

UN Special envoy of the Secretary-General for Syria Staffan de Mistura (L), and the delegation of the High Negotiations Committee (HNC) George Sabra (3rd R), Deputy head HCR, Asaad Al-Zoubi (2nd R), head of HCR, and Mohammed Alloush (R), Chief negotiator for the main Syrian opposition body and opposition group Army of Islam, attend prior a round of negotiations between the Syrian opposition and U.N., at the European headquarters of the United Nations in Geneva, March 18, 2016.

Reuters