KABUL - US President Barack Obama paid a surprised visit to Afghanistan on Sunday, an Afghan official told Xinhua.

The U.S. president arrived in the Bagram air base, the main US base in Afghanistan, late on Sunday.

Obama is not planning to meet President Hamid Karzai and the two leading presidential candidates of upcoming presidential runoff, local media reported.

The aim of his trip is reported to meet American soldiers and he will also visit the injured soldiers who got wounded in Afghanistan.

This is Obama's fourth trip to the war-hit Afghanistan.