FILE -- In this Monday Aug. 6, 2012 file photograph, Egyptian border guards patrol near the border with Israel in Rafah, Egypt. Egypt deployed helicopter gunships to the Sinai Peninsula on Monday to hunt for the militants who killed at least 16 soldiers Sunday when the troops at a checkpoint were having the traditional meal at the end of the daily fast during the Muslim holy month of Ramadan. After decades of neglect and with the collapse of government authority the past 18 months, Egypt’s Sinai Peninsula has become fertile ground for Islamic extremists. Militant groups have taken root, carrying out attacks against neighboring Israel and now turning their guns against Egypt’s military as they vow to set up an Islamic state. (AP Photo/Ahmed Gomaa, File)

CAIRO - Gunmen sprayed a police station in Egypt's Sinai with bullets Thursday, setting off a brief firefight with policemen before speeding away in their truck, the latest in a series of attacks against security forces in the increasingly volatile peninsula, security officials said.

Meanwhile, the military sent additional armoured and other army vehicles to boost its strength in a hunt for militants in the wake of a deadly weekend attack that killed 16 Egyptian soldiers.

The security officials also said army engineers were making preparations to destroy or shut an elaborate underground tunnel network linking Sinai and Gaza that is used to smuggle weapons, people and basic goods to circumvent border restrictions imposed against the Hamas-controlled territory by Israel and Egypt. The officials all spoke on condition of anonymity because they were not authorized to discuss ongoing operations.

The lawlessness in northern Sinai, which borders both Gaza and Israel, reached a new level with Sunday's attack on an Egyptian military border post. The attackers killed the 16 soldiers as they were breaking their daily fast for the holy month of Ramadan with a sunset meal. They then commandeered an armoured vehicle, which they later used to storm across the border into Israel where they were hit by an Israeli airstrike that killed at least six militants.

The attack has rattled the Egyptian government, prompting the country's new Islamist president to sack the intelligence chief for failing to act on an Israeli warning of an imminent attack just days before.

President Mohammed Morsi also sacked the northern Sinai governor. The decisions were Morsi's first moves to assert his authority amid a power struggle with the country's military leaders. But the decisions appeared to have come with the generals' approval as the nation was outraged by the militants' attack, the worst assault on troops from within Egypt in living memory.

The military also announced an offensive in Sinai designed to weed out the militants who have used the security vacuum in the desert region to spread their influence. In a sharp escalation, Egyptian warplanes struck against suspected militant hideouts on Wednesday, but there were no official reports of deaths or arrests in the operation.

The United States voiced support for Egypt's efforts to improve security in the peninsula and vowed more counterterrorism co-operation with its longtime ally.

Large swathes of northern Sinai have plunged into lawlessness following the ouster of Egyptian President Hosni Mubarak last year, with a massive flow of arms smuggled from Libya finding their way into the hands of disgruntled Bedouins. The lawlessness is coupled with the rise of al-Qaida-inspired militant groups that are waging a campaign of violence in the peninsula against Egyptian security forces. They have also staged several cross-border attacks on Israel.

Despite the new offensive, attacks against troops have continued, in an apparent message by the militants that they are undeterred.

No one was hurt in the Thursday morning attack on a police station in the northern Sinai city of El-Arish, the security official said. The official also said military helicopters were circling the skies to provide cover for forces on the ground and track militants in mountainous areas unreachable on foot.

Several past campaigns, in which the tunnels were either blown up, filled with water or shuttered down, have failed to stem the lucrative Gaza smuggling. A metal underground fence installed by Egypt has also failed to deter diggings of new tunnels. Meanwhile, Egyptian authorities have kept the Rafah border crossing with Gaza closed to passengers since the attack last weekend.

The military has also urged citizens and local Bedouins to assist it in tracking militants in Sinai.

News from © The Associated Press, 2012