US Secretary of State Antony Blinken offered Niger's ousted leader Mohamed Bazoum Washington's steadfast support, and warned those detaining him that "hundreds of millions of dollars of assistance" was at risk, the State Department said Friday.

General Abdourahamane Tchiani, head of the Presidential Guard since 2011, has declared himself the new leader of Niger after a coup earlier this week in which the pro-Western Bazoum was detained.
Blinken, who was wrapping up a multi-nation Pacific tour, called Bazoum for the second time in as many days to offer America's "unflagging support," department spokesman Matt Miller said in a statement.

The US secretary of state also "praised Bazoum's role in promoting security not only in Niger but the wider West Africa region," and said Washington would keep working to "ensure the full restoration of constitutional order and democratic rule in Niger."

In a separate call to former Nigerien leader Mahamadou Issoufou, Blinken expressed concern over Bazoum's ongoing detention, and that "negotiations to ensure constitutional order in Niger were at an impasse."

He told Issoufou that he "regretted that those detaining Bazoum were threatening years of successful cooperation and hundreds of millions of dollars of assistance" to Niamey, and asked Issoufou to keep working on Bazoum's behalf, Miller said.

Washington had already warned it could cease security and other cooperation with Niger, where about 1,000 US troops are stationed -- for now.

Blinken also spoke with French Foreign Minister Catherine Colonna about the situation in Niger, emphasizing the "urgency of efforts to restore constitutional order" in the jihadist-hit West African nation.