A top aide to U.S. President Barack Obama on Friday called for resolution of the political crisis in Yemen through a serious dialogue.

John Brennan, the president's assistant for counter-terrorism and homeland security, called Yemeni President Ali Saleh to welcome his initiative to resolve the political crisis in Yemen, a key partner in U.S. efforts to fight the al-Qaida in the Arabian Peninsula.

Brennan called on representatives of all sectors of the Yemeni opposition to "respond constructively to President Saleh's call to engage in a serious dialogue to end the current impasse," the White House said in a statement.

Saleh launched on Thursday a fresh conciliation initiative, promising to hold a referendum on the constitution this year in preparation for transferring power to parliament.

Brennan said the government and the opposition share responsibility for achieving a peaceful resolution of the crisis, noting that a commitment by all sides to participate in an "open and transparent" process that addresses the legitimate concerns of the Yemeni people provides "an orderly path" to a stronger and more prosperous nation.

The White House said that Saleh reiterated his hope that the opposition will engage immediately in a dialogue with the government as well as his public assurance not to use violence against peaceful demonstrators.

Month-long protests against Saleh have been escalating across the country since he rejected an opposition's peaceful road-map initiative earlier this week, which offered him a smooth transition for power within this year.

The United States has been aiding Yemen in its fight against the al-Qaida, which has tried to bomb targets on U.S. soil.