British Foreign Secretary Philip Hammond on Monday welcomed the inauguration of the newly elected Afghan President Ashraf Ghani Ahmadzai.

"The inauguration of President Ashraf Ghani Ahmadzai today marks the first democratic transfer of power in Afghanistan's history. This is truly an historic moment, made possible by the millions of Afghans who turned out to vote in April and June," Hammond said in a statement.

He added that former Afghan President Hamid Karzai has led Afghanistan "skillfully" through a turbulent time in the country's history.

The foreign secretary noted that Britain is committed to "working with his successor, President Ghani, his Chief Executive Dr Abdullah and the government of national unity to help improve the lives of all Afghans."

Ghani was sworn in on Monday, marking the first-ever peaceful power transition in the country's history. After his swearing-in, Ghani appointed his opponent Abdullah Abdullah as chief executive officer of the new Afghan government.

The newly created chief executive post is equal to that of a prime minister in the national unity government agreed upon by the duo, after more than a three-month standoff over disputed election results.

Some 1,400 national and international dignitaries, including 200 delegates from the United States, China, Pakistan, India and other countries attended this first-ever peaceful power transition ceremony in Afghanistan.

The country's election commission on Sept. 21 announced Ghani Ahmadzai as successor to Karzai.

The new government under Ghani Ahmadzai is set to sign the Bilateral Security Agreement (BSA) with Washington on Tuesday to allow limited number of the US troops to remain in Afghanistan after 2014 withdrawal of the NATO-led forces from the country, the president's national security advisor Rangin Dadfar Spanta said on Saturday.