US Ambassador to Russia Jon Huntsman has submitted a resignation letter and is planning to leave his post in early October, US media reported on Tuesday.

"I humbly resign my office as United States Ambassador to Russia, effective October 3, 2019," Huntsman wrote in the resignation letter to President Donald Trump, which was first reported by The Salt Lake Tribune.

Huntsman, US Ambassador to Russia since 2017, said in the letter that he had notified the president and State Secretary Mike Pompeo about his decision to end the two years of service to "reconnect with our growing family and responsibilities at home."

"Going forward, we must continue to hold Russia accountable when its behavior threatens us and our allies," the ambassador said, also noting that it is critical for Washington and Moscow to increase exchanges of people and maintain channels for dialogue on various issues of national interest.

According to US media, Huntsman is mulling another run for governor of Utah.

Huntsman's resignation came during a difficult period of bilateral relations. The United States last week imposed a new round of sanctions on Russia over the poisoning of a former Russian spy in Britain in March 2018. The two countries also had abandoned the Intermediate-Range Nuclear Forces (INF) Treaty, after years of trading accusations.

Huntsman served as US Ambassador to China from 2009 to 2011, and prior to that he was the governor of Utah.