U.S. President Barack Obama, who unexpectedly arrived in Afghanistan earlier on Sunday and met with his Afghan counterpart Hamid Karzai, said he wanted to see progress continue on Afghan efforts to tackle corruption and drug-trafficking, local radio reported.

The U.S. president''s helicopter landed at Afghanistan''s Bagram Air Base at 7:25 p.m. local time (15:55 GMT), after a 12-hour and 46-minute nonstop overnight flight. Obama''s first trip to Afghanistan as commander-in-chief was not previously announced due to security concerns.

About half an hour later, Obama''s helicopter touched down at presidential palace in Kabul.

According to a pool report by Wall Street Journal correspondent Peter Spiegel, during a meeting with Karzai, the U.S. president reportedly intended to "make him understand that in his second term, there are certain things that have been not paid attention to", namely, a "merit-based system for appointment of key government officials, battling corruption, taking the fight to the narco-traffickers, which fuels, provides a lot of the economic engine for the insurgents."

Local radio reports said Obama invited Karzai to visit Washington for bilateral talks in May.

Karzai''s relations with the West were strained last year by his fraud-tainted reelection in November. The U.S. has repeatedly called for the Afghan leader to take steps to clean up corruption in his government.