BAQUBA: A suicide bomber rammed an ambulance packed with explosives into a security headquarters on Wednesday, killing 13 people in the second major attack against Iraqi forces in as many days.

A second suicide attack in a nearby town killed two others and wounded a top provincial official, shattering a relative calm in Iraq following the formation of a new government by Prime Minister Nuri al-Maliki last month.

“We have so far received 13 bodies, and are treating 64 wounded,” said Firaz al-Dulaimi, a doctor at Baquba hospital, referring to the first attack on Wednesday morning in the Diyala provincial capital.

The 10:00 am (0700 GMT) bomb in the middle of Baquba, a restive ethnically mixed city north of Baghdad, targeted an office of the Force Protection Service (FPS), the agency responsible for securing government buildings.

The explosion also damaged nearby buildings, including the al-Batool women and children's hospital, and AFP journalist said.

Three young children and their teacher were wounded at a nursery school, an official at Diyala Operations Command said.

Local officials imposed a vehicle curfew on Baquba, not allowing any cars in or out, and security forces cordoned off the scene of the blast.

The operations command official, speaking on condition of anonymity, said the FPS office had received a call from an individual purporting to work for the provincial health department, notifying them that an ambulance would be arriving, helping the attacker get close to his target.

About 90 minutes later in the nearby town of Ghalbiyah, a suicide bomber blew up his explosives-filled car in the midst of a crowd of Shia pilgrims, killing two and wounding 16 other people, an official in the provincial security command said.

Among the wounded were Diyala deputy governor Sadiq al-Husseini and three of his bodyguards, and two media employees of local satellite channel Diyala TV.

Husseini was visiting with worshippers as they gathered ahead of commemorations for Arbaeen, which marks 40 days since the anniversary of the death of the revered seventh century Shiite Imam Hussein.

The attack also triggered a fire at a nearby petrol station.

Diyala was an Al-Qaeda stronghold as recently as 2008. While violence has dropped off dramatically both in Diyala and nationwide since then, the province remains one of Iraq's least secure.

The attacks came a day after a suicide bomber detonated an explosives-packed vest in the middle of a crowd of police recruits in the central city of Tikrit, killing 50 people and wounding up to 150.

It was the deadliest attack to hit Iraq in more than two months, and the first major strike since Maliki named a new cabinet on December 21, ending nine months of stalemate after March elections.

Tikrit's police chief Colonel Ibrahim al-Juburi and the head of the city's emergency response squad Brigadier General Mohammed Majeed were fired in the aftermath of the blast.

Maliki condemned the Tikrit attack, saying “terrorists” had once again targeted the innocent.

“Once again the terrorists returned to their usual tactics of killing the innocent and targeting the brave young people who wanted to serve their country and defend it,” he said in a statement Tuesday evening.

“We will follow the case closely until we find who is responsible, and the reasons that let this tragic catastrophe happen.” Violence across Iraq has declined substantially since its peak in 2006 and 2007, but attacks remain common.