KABUL (Reuters) - A suicide bomber blew himself up at an Afghan Defence Ministry gate in Kabul on Saturday during a visit by U.S. Defense Secretary Chuck Hagel, a coalition spokesman said, underscoring security problems as NATO troops prepare to leave.

Hagel was nowhere near the explosion, said a spokesman for Afghanistan's NATO-led International Security Assistance Force (ISAF). A U.S. defence official said Hagel was in a safe location at an ISAF facility.

A Defence Ministry official said there were civilian casualties but did not specify.

The Afghan Taliban claimed responsibility for the attack and said the ministry was the target. They said in a statement the attack "is a kind of message" for Hagel.

The blast underscored the security challenges facing Afghanistan as U.S.-led NATO forces prepare to leave the country by the end of 2014.

Hagel arrived in Afghanistan on Friday for his first trip abroad as defense secretary, seeking to make his own assessment of America's longest war as it enters its final stretch.

Hagel said he would meet U.S. commanders and troops, and hold talks with President Hamid Karzai, whose recent orders to curtail U.S. military activity highlights an often tense relationship with the 66,000 American forces here.

Hagel is making his first trip to Afghanistan since a mid-2008 visit with then-Senator Barack Obama during Obama's campaign for the presidency.

Obama, a Democrat, forged a close bond with Hagel, a Republican, and remarked later that summer that the two agreed on almost "every item" of foreign policy.

Hagel was confirmed as defense secretary on February 26 and was sworn into office the next day.

His advice may help shape some of Obama's most lasting decisions in Afghanistan, notably how large a residual mission to keep there once NATO wraps up its combat mission at the end of next year and the vast majority of foreign forces go home.

On Tuesday, the outgoing head of the U.S. military's Central Command, General James Mattis, disclosed that he recommended keeping 13,600 American troops in Afghanistan - above the range of troop levels U.S. officials have said were being considered by the White House and discussed by NATO defence chiefs last month.

Obama last month announced the withdrawal of 34,000 American troops - about half the total - by early next year. Officials also have outlined the expected pace of the withdrawal through next April.

Hagel, a decorated Vietnam war veteran with shrapnel wounds in his chest, has played down links between Vietnam and the grinding, counter-insurgency battle in Afghanistan. Despite 11 years of fighting and significant gains in Afghanistan, the Taliban remain resilient and enjoy safe havens across the border in Pakistan.

(Additional reporting by Phil Stewart; Writing by Michael Georgy; Editing by Jeremy Laurence and Robert Birsel)

Related Stories:
Suicide bombing in Kabul kills nine people during Hagel visit

• Malaysia tycoon Vincent Tan plans IPO of football club Cardiff City
• Google, like Facebook, in talks to buy Waze for about US$1bil
• Crown selling entire 10% in rival Echo, partly owned by Genting(Update)
• First edition of 'Great Gatsby' to be sold at auction, can fetch US$150,000
• Malaysia leads the way in Basel III debt
• Markets face rough summer ride as Fed pullback feared
• Wall Street sags, HP hits 52-week high
• Commodities trader sues BP, Shell others for alleged oil price fixing
• Billionaire Icahn seeks up to US$7bil for Dell bid
• Google faces new federal antitrust probe
• Goldman Sachs unveils checks on conflicts in bid to fix tarnished image
• Air Asia's Tony Fernandes to ‘fire up’ investors
• Maybank bullish on growth, to expand regionally under new leadership
• Khazanah appoints Nor Mohamed deputy chairman
• Lafarge Malayan Cement to finalise next expansion plans by August

• Cars, schools ablaze in fifth night of Stockholm riots
• London's Heathrow airport closed after emergency landing
• Far East quake felt in Moscow, tsunami warning lifted
• Police make new arrests in London soldier killing
• Britain's press demands jailing of Islamist preacher
• Tsunami warning in Russia's Far East after 8.2 quake
• US bridge collapse sends cars, people into river
• Strong quake strikes off Tonga
• Jury fails to decide on US murderer death sentence
• One killed in Brazil giant fuel depot blaze

• Kingston leads, McIlroy in Wentworth woe
• LPGA plans 12-hole rounds in water-logged Bahamas
• Ryan Palmer sizzles with 62 to seize lead at Colonial
• Kelly overcomes scare to clinch title in KLGCC
• Time to make amends Garcia wants to meet Woods to defuse racist row
• American Johnson back to defend Colonial crown
• Rain dampens debut of LPGA Bahamas event
• Tianlang adds another US event to schedule
• Clock ticking for next golden generation
• Nadal wants to create history at Roland Garros
• Serena out to tame French Open demons
• Zheng Jie stuns Wozniacki in Brussels
• British Open: Ramy Ashour racks up 38th successive win
• Nicol David sails into quarter-finals of British Open in 35 minutes
• BAM must stop rewarding mediocrity or be doomed

• Please wait.

• Air Asia's Tony Fernandes to ‘fire up’ investors
• Singapore GDP growth surprises, beats economists’ forecast of contraction
• KL car number plates to bear ‘W1A’
• Tian, Tamrin and Haris released after remand denied (updated)
• Malaysia leads the way in Basel III debt
• Inventions a-plenty, but no real innovation
• Robber shot dead after attacking out-of-uniform cop with meat cleaver
• Three held over May 13 statements
• Fernandes does his first firing in Apprentice Asia
• Wall Street sags, HP hits 52-week high