American teacher Ronnie Smith has been shot dead by militants while jogging in Libya's eastern city of Benghazi, local officials said.

Smith, from Texas, taught chemistry at an international school in the city, medical and security forces reported.

He was taken to the al-Galaa hospital in Benghazi where he was pronounced dead.

On his twitter page under the username @ISBchem, Smith wrote in his bio that he was "Libya's best friend".

He was jogging in Fweihat district when he was shot by an unknown group. No one has claimed responsibility for the attack.

"He was doing his morning exercise when gunmen just shot him. I don't know why. He was so sweet with everyone," said Adel al Mansouri, director at the international school.

The international school in Benghazi is an institute that follows an American curriculum.

Smith's death comes 15 months after the US ambassador to Libya, Christopher Stevens, was killed when Islamist militants launched an attack on the US consulate in Benghazi.

Smith described himself as \'Libya\'s best friend\' on his social media profile (Twitter)