Iraqi Prime Minister Nouri al-Maliki has vowed to confront perpetrators of violence following a recent spate of car bombings in and around Baghdad that left at least 68 people dead.

In a show of cabinet unity, al-Maliki appeared on Tuesday with four leading ministers, including the country's two most senior Sunni politicians, to speak of his government's insistence on facing down the fighters.

"The cabinet discussed seriously today all the challenges facing the security situation and the steps that the council of ministers should adopt to confront the current crisis" he said.

"The cabinet has unanimously agreed to stand as one to confront the crisis and to send a message of reassurance that all are in agreement on shouldering their responsibility in confronting the outlaws regardless of their affiliation, sect or political party they belong to."

Just hours before, at least five people were killed and 26 others wounded as a bomb exploded on a bus in the Shia-majority neighbourhood of Sadr City in eastern Baghdad.

Five policemen and 20 civilians were wounded in the attack, according to police.

Elsewhere, police reported that a suicide bomber set off his explosives-laden truck after passing a police checkpoint in the town of Tarmiyah north of Baghdad, killing a policeman and a civilian. Nine were wounded.

Al-Maliki said he would pursue the perpetrators who were aiming to ignite a civil war.

"We will chase down all the illegal militias and armed gangs that want to instigate a wave of societal fighting. As far as we are concerned this constitutes a red line."

Tuesday's attacks are the latest in a spike of killings that has claimed more than 400 lives since the start of May, making it one of the country's bloodiest months in recent history.

'Dangerous unknown'

In the northern city of Mosul, about 360km from Baghdad, clashes erupted between police and armed men, following a roadside bomb attack.

Three policemen were killed in the clashes, officers said. Four gunmen were killed and 15 others arrested.

Al Jazeera's Jane Arraf, reporting from Baghdad, said the deputy head of police intelligence died in the shoot-out.

South of Mosul, a bomb hit a police patrol, killing an officer and wounding another, police said.

Alarmed by the recent bloodshed, UN envoy Martin Kobler pressed Iraqi leaders on Tuesday to do more to halt the violence, saying it is "their responsibility to stop the bloodshed now".

Kobler has repeatedly urged Iraqi officials to engage in dialogue as violence and political tensions have grown in recent weeks.

He warned political leaders not to let fighters benefit from their political differences, and predicted that "the country will slide into a dangerous unknown if they do not take immediate action".

No one has claimed responsibility for the recent wave of attacks.

Bombings on Shia and Sunni mosques, security forces and Sunni tribal leaders over a month-long surge in violence are deepening worries Iraq may tip back into the kind of widescale sectarian violence that killed thousands in 2006-2007.

Tensions between the Shia-led leadership and the country's Sunni Muslim community are at their worst since American troops left in December 2011.

Source: Al Jazeera and agencies