Baghdad, May 7 (IANS): At least four security personnel were killed and 16 wounded on Thursday when a suicide bomber struck a military base west of the Iraqi city of Tikrit, a provincial security source said.

The bombing occurred early Thursday morning, when a suicide bomber drove his explosives-laden tanker truck into the base that houses Iraqi police and allied militias known as Hashd Shaabi (Popular Mobilisation) in Shajarat al-Dur area, just west of Salahudin province's capital Tikrit, some 170 km north of the Iraqi capital of Baghdad, the source told Xinhua news agency.

The huge blast was immediately followed by an assault by dozens of Islamic State (IS) militants.

The toll could rise as the fighting was still going on, the source said.

Since March 2, some 30,000 Iraqi troops and allied Shia and Sunni militias have been involved in Iraq's biggest offensive to recapture the northern part of Salahudin province, including Tikrit and other key towns and villages, from IS militants.