Kabul, Afghanistan ? Britain’s defense secretary warned Sunday that any letup on militants could see the toppled Taliban regime and al-Qaida regain power in Afghanistan.

As John Reid made his call during a visit to Kabul, gunbattles elsewhere killed five people and rockets slammed into a U.S.-run base in the south.

The warning followed a spike in bombings and shootings targeting coalition troops, Afghan forces and often ordinary locals as the Taliban apparently have made good on threats to increase attacks during the warmer spring and summer months.

“The greatest danger of all for the people of Afghanistan and the people of the United Kingdom would be if Afghanistan ever again came under the rule of a Taliban regime prepared to protect al-Qaida or terrorist groups,” Reid told reporters in the capital.

Spiraling violence is a growing concern for nations contributing troops to a force operating here under a NATO mandate. The force is to rise from its current 10,000 soldiers to about 21,000 by November as it gradually assumes command of all international troops in Afghanistan.

Some 6,000 mainly British, Canadian and Dutch soldiers have started deploying in the remote tribal-dominated southern region

At least 18,000 U.S. soldiers are in Afghanistan – more than four years after the U.S.-led invasion toppled the hard-line Taliban regime for hosting al-Qaida leader Osama bin Laden.

Reid said coalition forces were based throughout southern Afghanistan primarily to aid the war-ravaged country’s reconstruction, but also were prepared to defend Afghan partners and themselves.

A man prays as a truck carries the wreckage of an old airplane destroyed during the civil war in Kabul, Afghanistan, Sunday, April 23, 2006.

Afghan soldiers and police surrounded Taliban fighters hiding in a village in the volatile Gelan district of southern Ghazni province, some 75 miles southwest of Kabul, said provincial Gov. Haji Sher Alam. Three Taliban fighters and a policeman were killed, he told The Associated Press.

Elsewhere in the south, a group of heavily armed Taliban militants attacked an Afghan construction company working for coalition forces before dawn Sunday, killing one security guard and wounding two others before remaining security personnel fled.

The two-hour battle raged at the headquarters of the Thavazoo company in Shah Wali Kot district, about 25 miles north of the city of Kandahar, said Haji Mohammed Youssef, the company’s director.

The Taliban fighters entered the compound after the security fled, burning 14 trucks and bulldozers and stealing equipment before escaping, said Youssef, whose company won a contract from the coalition forces to build a 25-mile stretch of road.

“Coalition forces are giving us money to help rebuild our country, but the enemies of Afghanistan don’t want us to succeed,” he told AP.

The attack happened on the Uruzgan-Kandahar highway near a southern Kandahar village where four Canadian soldiers were killed in a suspected Taliban roadside bombing a day earlier.

Militants also fired four rockets into the U.S.-led coalition base in Kandahar, but no casualties or damage were reported, Canadian military spokesman Maj. Quentin Innis said.

On Saturday, U.S. and Afghan soldiers arrested 16 Taliban members in the southern Zabul province, which neighbors Kandahar.

“The Americans are questioning them now to see if they are important Taliban members or not,” local Afghan army commander Gen. Rahmattalluh Roufi said.