United Nations Secretary-General Ban Ki-moon has appointed Slovak diplomat Jan Kubis as his special representative and head of the U.N. mission in Afghanistan.

Kubis succeeds Staffan de Mistura of Sweden, who will complete his tenure on December 31, 2011.

In a statement Wednesday, Mr. Ban said he was grateful to Mistura for his dedication and leadership of UNAMA, serving in one of the most challenging duty stations during the most challenging times.

The statement said Kubis, who has served as the executive secretary of the U.N. economic commission for Europe since 2009, brings with him more than three decades of experience in the areas of diplomacy, foreign security policy, and international economic relations.

In violence Wednesday, joint Afghan-coalition security forces captured several Taliban and Haqqani network leaders across the country.

A NATO statement says Taliban leader Wali Mohammad and four of his associates were detained in Nahr-e Saraj district of southern Helmand province. Mohammad was behind numerous suicide and other attacks against local civilians. The security force also seized a large quantity of bomb-making materials.

Another Taliban leader was apprehended in the eastern province of Nangarhar, while at least two Haqqani network leaders, along with multiple suspected insurgents, were intercepted in eastern Logar, Khost and Paktika provinces bordering Pakistan.