WASHINGTON,  (Reuters) – President Barack Obama said  yesterday he has terminated trade benefits for Guinea,  Madagascar and Niger, three African countries where democratic  progress is threatened by political turmoil.

In a statement, Obama said the three countries had failed  to make “continual progress” in meeting U.S. requirements for  the African Growth and Opportunity Act.

At the same time, Obama said he was adding Mauritania to  the list of sub-Saharan African countries eligible for  preferential U.S. tariff treatment under the program.

Separately, the State Department said the United States had  suspended non-humanitarian aid to Niger and imposed travel bans  on some government officials in response to Niger President  Mamadou Tandja’s moves to extend his time as leader.

Tandja’s original term was to end on Dec. 22.

Earlier this month, Obama sent Tandja a message calling for  more democracy in Niger. The United States has also frozen $20  million in aid for Niger under its U.S. Millennium Challenge  Corporation agreement with the country.

A United Nations report on Monday blamed Guinea’s junta  leader Moussa Dadis Camara for the Sept. 28 killings of more  than 150 pro-democracy marchers by security forces.

Guinea, the world’s top exporter of bauxite and a pivotal  country for the security of West Africa, has been on the brink  of chaos since the massacre and a botched assassination attempt  against Camara on Dec. 3 by his former aide de camp.

Madagascar’s security forces yesterday fired teargas at  opposition leaders and hundreds of their supporters outside  parliament as political tensions escalated on the Indian Ocean  island.

The brief flare-up happened near the national assembly  where the opposition plans to form a new parliament, a process  President Andry Rajoelina says is illegitimate.

The United States provides duty-free treatment for nearly  6,400 eligible items such as clothing, cocoa, wood, leather,  processed foods and cut flowers under the African Growth and  Opportunity Act. However, the biggest single import under the  program is oil.

To be eligible, countries must at least be making continual  progress toward establishing the rule of law and political  pluralism, the protection of human rights and workers rights  and efforts to fight corruption.

The United States imported $324.3 million worth of goods  from Madagascar, $106.4 million from Guinea and $44.3 million  from Niger in 2008.