US Secretary of State John Kerry paid an unannounced visit to Afghanistan on Monday for talks with President Hamid Karzai, a US official said.

Kerry and Karzai will discuss a host of issues including Afghan reconciliation, the transfer of security responsibility to Afghan forces as most foreign troops prepare to leave and Afghanistan's elections, the U.S. official told reporters.

The United States and Afghanistan are hoping to stabilise the country before most U.S.-led NATO combat troops leave by the end of 2014.

Karzai's government is trying to open formal negotiations with the Taliban, who have remained resilient in the face of superior NATO firepower in the war now in its 12th year.

Karzai is due to travel to Qatar within days to discuss the peace process and the opening of a Taliban office for the purposes of conducting negotiations.

Commenting on Karzai's trip to Qatar, the U.S. official told reporters: "I wouldn't want to overplay it but I think that it's a very positive sign. It's another step on a continued path toward ... getting to some sort of reconciliation process.

"Nobody is expecting that he will open an office there in a week. Nobody is expecting that he will be sitting down with Taliban in a week. This is a long process and this is one more small but positive step in that ... process." – Reuters