Iraq's parliament is to convene next week to begin the task of forming a new government after April's general elections.
Leaders from across the political spectrum are under pressure to form an inclusive process to present a united front against a rapidly advancing Sunni rebellion that threatens to spread across the region.
Khudeir al-Khuzaie, Iraq's vice president, on Thursday ordered parliament to re-convene next week, and urged parliament to hold its first session on Tuesday.
Parliament is expected to elect a speaker and two deputies, then within 30 days choose a new president who will ask the largest bloc to choose a prime minister and form the new government.
Iraq's incumbent prime minister, Nouri al-Maliki, had initially ruled out forming a new government, calling the idea a "coup" against the constitution.
At a meeting with Maliki in Baghdad on Thursday, William Hague, British foreign secretary, spoke on the need of forming an "inclusive government" to combat the Sunni fighters' offensive, echoing an earlier call by the US.
Hague, during his unnannounced visit, urged Maliki "to demonstrate to the world that Iraq is uniting in the face of this threat".
Sunni rebels led by Islamic State of Iraq and the Levant (ISIL) fighters have expanded their offensive, capturing vast swathes of five provinces north and west of Baghdad, close to the Syrian border.
Syrian air strikes
Hague's visit to Baghdad came as Maliki confirmed the Syrian air force had carried out strikes against ISIL fighters on the Syrian side of the al-Qaim border crossing, a position controlled by the rebels.
In an interview with the BBC, Maliki said Baghdad had not requested the Syrian strikes, but he "welcomed" the move.
Iraq had earlier appealed for US air strikes against the rebels, but the US had only offered up to 300 military advisers, the first of whom have begun work in Baghdad.
|Map: The Islamic State's (formerly ISIL) path through Iraq
The US had pressed for a national emergency government, and brushed off Maliki's insistence that such a move would be a "coup against the constitution and the political process".
The US government has ruled out sending ground troops to aid the Iraqi government, but has kept an option open to use air power.
It has moved a carrier-strike group and troops vessels into the Arabian Gulf area.
Israel offers to help
The region has been on high alert, with Iraq's neighbours threatened by the offensive by the Sunni rebels.
Against this backdrop, Avigdor Lieberman, Israel's foreign minister, offered on Thursday to help his "moderate" Arab neighbours.
Lieberman said "the extremists currently operating in Iraq will try to challenge the stability in the entire Gulf region, first of all in Kuwait".
"Israel could provide effective and reliable assistance to moderate Arab states who are dealing with extremists," a statement from Lieberman's office said.
Saudi Arabia, who shares a long border with Iraq, said it was reinforcing security against a possible fallout from the conflict.