The US Port of Long Beach has reained its "AA" rating on its outstanding debt from US credit agency Fitch.

Fitch listed several reasons for its US ports highest rating, including strong market position and "resilient revenues" from long-term contracts covering senior debt and a Transportation Infrastructure Finance and Innovation Act (TIFIA) loan.

Fitch affirmed the top rating on the port's $946m in senior lien harbor revenue bonds and notes from the City of Long Beach, California.