The US Treasury on Wednesday placed sanctions on two Indonesian men it said were closely involved with two radical Islamist groups behind attacks and bombings over more than a decade.

The Treasury blacklisted Said Ahmad Sungkar, 51, whom it said had been involved in fundraising and other support efforts for Jemaah Islamiya (JI) and Jemmah Anshorut Tauhid (JAT), both of which are officially designated by Washington as terrorist groups.

Afif Abdul Majid, 58, is a leader of JAT, helping with recruitment, and training activities for violent attacks, and in 2012 "played a role in coordinating the activities of regional JAT leaders," the Treasury said.

"The threats posed by terrorist groups such as Jemaah Islamiya and Jemmah Anshorut Tauhid remain significant," said Treasury Under Secretary for Terrorism and Financial Intelligence David Cohen in a statement.

"We will continue to take action to protect the international financial system from illicit activity tied to these groups, making it ever more difficult for them to carry out their acts of violence," he said.

The sanctions freeze any assets linked to the two under US jurisdiction and ban Americans from any business with them.

JI in particular has been tied to a number of deadly terror attacks, including the 2002 Bali bombings that killed 202 people.

JAT has carried out attacks against the Indonesia government.