A motorcycle suicide bomber killed the deputy governor of Afghanistan's Kandahar province on Saturday, a blow to U.S.-led forces trying to bolster governance and fight a robust insurgency in the Taliban's heartland.

Violence in Afghanistan is at its worst since U.S.-backed Afghan forces overthrew the Taliban in late 2001 with casualties on all sides at record levels and militant attacks increasing in number and spreading to almost every part of the country.

Deputy Governor Abdul Latif Ashna was killed as he left his home to travel to work in Kandahar city, capital of Kandahar province, the governor's spokesman Zalmay Ayoubi said.

At least five other civilians who were wounded in the blast had been taken to hospital. No further details were immediately available about the attack or about the condition of the wounded.

U.S. Ambassador Karl Eikenberry who was visiting Kandahar on Saturday condemned the attack but said it would not sap efforts to increase security in the southern province.

The loss of a great deputy governor like this is a setback. What we've seen is consistently Afghan government leaders emerge and the people continue to rally in an effort to establish security in this province, he told journalists.

ASSASSINATION CAMPAIGN

Kandahar is the spiritual homeland of the Taliban and has been the main focus of U.S. efforts over the past year to turn the tide of a war now in its tenth year.

Tens of thousands of foreign and Afghan troops have run clearing operations in some of the country's most volatile districts around Kandahar city, while Afghan police, mentored by foreign trainers, formed security perimeters inside the city.

But while the city has seen a drop in large-scale attacks over the past year, militants have managed to step up a campaign of targeted killings, particularly against government figures, which makes it hard to recruit officials.

Between mid-June and mid-September, 21 people were reported to have been assassinated each week across Afghanistan, up from seven a week for the previous three months, the United Nations said. Most killings took place in the south and east.

Alongside the military campaign, the United States has also ramped up its civilian presence in Kandahar to try and strengthen local governance and improve public services to encourage residents to support their government and reject the insurgency.

But in May, Frank Ruggiero, then the U.S. State Department's top official in southern Afghanistan and now acting top envoy to Afghanistan and Pakistan, said it was increasingly hard for civilians to work in Kandahar because of the assassinations.

Last year was the bloodiest for foreign troops in Afghanistan with 711 killed. But civilians bear the brunt of the war with 2,400 killed in the first ten months of 2010, U.N. figures show.

A war review by U.S. President Barack Obama last month said notable operational gains had been made and the Taliban's momentum arrested in much of the country.

But many critics dispute those assessments, pointing out that statistics show insurgent attacks are at their highest since the war started and some say optimistic messages about security are simply aimed at preparing for an eventual withdrawal.

Afghans are to begin taking over security in some provinces of the country in March, ahead of a gradual withdrawal of U.S. troops -- now numbering around 100,000 -- beginning in July.

This is part of a larger plan to have Afghan forces take the lead in securing the entire country by the end of 2014.

Barack obama United nations Pakistan Afghanistan