The US Treasury announced sanctions against Lebanon's former energy and foreign affairs minister Gebran Bassil on Friday, alleging he is behind corruption involving billions of dollars that has left the country's economy in shambles.

"The systemic corruption in Lebanon's political system exemplified by Bassil has helped to erode the foundation of an effective government that serves the Lebanese people," said Treasury Secretary Steven Mnuchin in a statement.

"This designation further demonstrates that the United States supports the Lebanese people in their continued calls for reform and accountability."

Bassil, the son-in-law of Lebanese President Michel Aoun and head of the mostly Christian Free Patriotic Movement party, is a senior politician involved in attempts to form a new government.

But the US sanctions announcement cited the country's ongoing electricity and garbage crises as results of deep corruption in government and said Bassil was "at the forefront" of graft in the country.

But it did not offer any specific details of the allegations.

"In 2017, Bassil strengthened his political base by appointing friends to positions and purchasing other forms of influence within Lebanese political circles," the Treasury said.

"In 2014, while Minister of Energy, Bassil was involved in approving several projects that would have steered Lebanese government funds to individuals close to him through a group of front companies."

"Bassil has repeatedly used his influence to stall government formation efforts, most recently in the current process, which has further delayed any chance of Lebanon pursuing meaningful economic reform," a senior government official said.

"With today's action, we encourage Lebanon to form a government that excludes politicians known to have engaged in corruption and to pursue meaningful economic reform."

However, the official insisted that the action Friday had "nothing to do" with the US election or attempts to form a government in Lebanon.

Another US official also said that Bassil's party is "closely aligned" with Hezbollah, the Lebanese political and military movement that Washington has labelled "terrorist" and sought to isolate through court cases and sanctions.

Friday's sanctions announcement seeks to freeze any of Bassil's assets under US jurisdiction and prevent him from accessing the global financial system.