Kabul/Washington  - US President George W Bush arrived in Afghanistan early Monday on a surprise farewell visit, committing the United States to establishing a stable democracy there as violence is on the rise and he prepares to leave office in five weeks.

Bush was to meet Afghan President Hamid Karzai and US troops on his visit, the details of which were shrouded in secrecy as the country and its foreign allies battle a Taliban and al-Qaeda insurgency.

"We have a strategic interest and I believe a moral interest in a prosperous and peaceful democratic Afghanistan, and no matter how long it takes, we will help the people of Afghanistan succeed," said Bush, who ordered the US-led invasion of Afghanistan in late 2001, which unseated the Taliban.

Speaking to US troops on his arrival at Bagram air base outside Kabul, Bush admitted that the goal of establishing a thriving democracy in Afghanistan was "a difficult and long effort" but added, "We want to lay the foundation of peace for generations to come."

The president flew to Afghanistan from Iraq, where he made an unannounced visit Sunday and met with President Jalal Talabani and Prime Minister Nuri al-Maliki.

The visits were likely to be his last to the two war-torn countries as US president. President-elect Barack Obama takes office on January 20. (dpa)