WASHINGTON: The US authorities have named Sirajuddin Haqqani, brother of Haqqani Network chief Aziz Haqqani, a "specially designated global terrorist", the State Department said in a statement.
"For several years, Aziz Haqqani has been involved in planning and carrying out improvised explosive device attacks against Afghan government targets," the State Department said on Tuesday.
According to the statement, Aziz Haqqani also "assumed responsibility for all major Haqqani Network attacks after the death of his brother, Badruddin Haqqani".
Aziz already had a $5 million US bounty on his head and the Haqqani faction has long been designated a "terrorist organisation".
He now joins his brother as subject to the seizure of any assets he may have in areas under US control, while Americans are banned from doing business with him.
Sirajuddin was last month named as one of two deputy leaders of the Afghan Taliban.
The Haqqani Network was set up in the 1970s as a force to oppose the Marxist regime in Kabul and its Soviet backers, and fought in the Afghan civil war.
US intelligence holds it responsible for some of the most audacious strikes of the insurgency, including the 2009 Camp Chapman bombing, which killed seven CIA agents.
"The Haqqani Network has planned and carried out a number of significant kidnappings and attacks against US interests in Afghanistan, as well as Afghan government and civilian targets," the statement added.
The Haqqani Network has close ties with Al Qaeda and has been blamed for many of the most deadly attacks against US and government targets in Afghanistan.
The US State state department designated the Haqqani Network as a Foreign Terrorist Organisation in September 2012.