With Iraqi President Jalal Talabani in Germany for treatment, the country has been without a key mediator during a disastrous year of political conflict and surging violence.

Talabani, a veteran Kurdish leader who is now 80, left Iraq for treatment on December 20 last year after suffering a stroke two days before, and has yet to return.

His skills as a mediator, who has sought to bring together feuding politicians, Sunni and Shiite, Arab and Kurdish, during the repeated political crises that have plagued Iraq since the US-led invasion of 2003, have been sorely missed in his absence.

"Talabani's absence affected the political elite and relations between them in a major way, as he was able to adjust the political game and prevent things from getting out of control," said Ihsan al-Shammari, a political science professor at Baghdad University.

"This year was the hardest for Iraq in years, and Iraq lived it without the protector and the sponsor of the constitution," he said, referring to Talabani's role as president.

Without him, Iraq's various branches of government and institutions "became chaos," Shammari said.

The day Talabani left the country, security forces arrested guards of then-finance minister Rafa al-Essawi, an influential Sunni Arab politician, on terrorism charges.

The arrests -- seen in Iraq's minority Sunni Arab community as just the latest example of the Shiite-led government targeting one of their leaders -- sparked a political crisis.

Protests -- which are still ongoing -- broke out soon afterwards, and quickly became about far more than Essawi.

There is widespread resentment among Sunnis at heavy-handed tactics by security forces in areas where they form the majority, such as mass arrests.

The discontent has been a key factor in a sharp rise in violence this year, boosting recruitment for militant groups and decreasing cooperation with security forces.

In the first quarter of 2013, violence was already up on preceding months. But then security forces stormed a Sunni protest camp near the northern town of Hawijah on April 23, sparking clashes in which dozens of people died.

Deaths tolls spiked, reaching a level not seen since 2008, when the country was just emerging from a brutal period of sectarian killings.

The violence, which was been further exacerbated by the civil war in neighbouring Syria, has killed more than 6,550 people since the beginning of 2013, according to AFP figures.

'Safety valve'

The government has responded with a security crackdown, but has left the underlying political grievances largely unaddressed.

Issam al-Faili, a political science professor at Mustansiriyah University in Baghdad, said that Talabani might have been able to lessen the damage, had he been present.

"Talabani was the safety valve, because he was above all sectarian and ethnic divides," Faili said.

"He was able to create approaches and political initiatives that could have made the past year less harmful."

In addition to his missing skills as a mediator, Talabani's absence also left the country effectively without a president, with the constitutional criteria for when a replacement should be selected unclear and the political will to do so lacking.

The Iraqi constitution says that "the vice president shall replace the president in case of his absence," but also that if the presidency becomes "vacant," a new president must be elected within 30 days.

It does not however elaborate on the distinctions between the two scenarios.

Shammari said that Talabani's absence, "although it is for medical reasons, assures us that Iraq is passing through a constitutional crisis."

"There is a constitutional gap that has not been addressed for many reasons," among them "the fragile political alliances, which mean that Talabani will continue in his post while he is outside Iraq until his mandate is over" next year.

Talabani's office has published periodic statements asserting that his health is improving, including one this month accompanied by photographs of him with his wife.

But it has yet to specify whether he will return, or if he will be able to carry out his duties were he to do so.

"Photos of Talabani that are being published from time to time are aimed at extending the process of turning a blind eye to the subject of finding a replacement for him," Shammari said.

"In any case, it is very hard at this time to find a replacement for Talabani who has the same charisma."