July 19, 2008, Kabul Afghanistan - US Democratic presidential hopeful Barack Obama arrived in Afghanistan Saturday to visit troops and assess efforts against extremist violence at the start of a major international tour, officials said.

Obama will meet Afghanistan's President Hamid Karzai on Sunday, the Afghan government said. He will also visit some of the 36,000 US soldiers in Afghanistan, many of them in the east of the country along the border with Pakistan.

"I'm looking forward to seeing what the situation on the ground is," the presumptive Democratic presidential nominee told reporters before leaving the United States.

"I want to, obviously, talk to the commanders and get a sense, both in Afghanistan and in Baghdad of, you know, what ... their biggest concerns are. And I want to thank our troops for the heroic work that they've been doing."

US government and military officials in Kabul were tight-lipped about Obama's movements in Afghanistan, with high-profile visits usually under wraps because of the threat from insurgents like the Taliban.

He is due to travel on to Iraq Monday and then to Jordan, Israel, Germany, France and Britain.

The Illinois senator said in the days building up to the tour that Afghanistan needs more help as it battles the Taliban-led insurgency.

If he wins the November elections, he plans to commit at least two more combat brigades, up to 10,000 men, to Afghanistan while downscaling the size of the force in Iraq.

"We need more troops, more helicopters, better intelligence-gathering and more non-military assistance to accomplish the mission there," Obama said in the New York Times on Monday.

"Iraq is not the central front in the war on terrorism, and it never has been."

In a major foreign policy address on Tuesday, Obama reiterated his promise to get most US combat troops out of Iraq within 16 months, and to focus on Al-Qaeda havens in Pakistan and Afghanistan.

"Al-Qaeda has an expanding base in Pakistan that is probably no farther from their old Afghan sanctuary than a train ride from Washington to Philadelphia," Obama said.

"We cannot tolerate a terrorist sanctuary, and as president I won't."

The insurgency that is hobbling Afghanistan's attempts to recover from decades of war was launched after the Taliban were removed from government in late 2001 in an invasion led by the United States.

The hardliners were attacked after they refused to hand over Al-Qaeda leaders for the 9/11 attacks that killed around 3,000 people in Washington and New York.

In one of the deadliest attacks on foreign troops since they deployed here in 2001, nine US soldiers were killed July 13 when about 200 insurgents stormed a base a remote outpost in the northeast. Another 15 soldiers were wounded.

A week earlier, Kabul was struck by its deadliest suicide attack when a car bomb blew up outside the Indian embassy. Around 60 people were killed including two senior Indian diplomats.

In new violence Saturday, four Afghan police officers were killed and another was injured when a bomb struck their vehicle in the southern province of Kandahar, police and a medic said.

The Taliban claimed responsibility for the remote-controlled explosion.

Also in Kandahar province, a suicide bomber blew up near a police post Saturday, police said. A police officer and a child were wounded, police officer Mohammad Nabi told AFP.

The United States contributes around half of the nearly 70,000 international soldiers in Afghanistan with around 40 countries pledging troops to fight the insurgency which makes heavy use of suicide attacks..