Nine American Shipping Co (AMSC) tankers will stay in the employ of Overseas Shipholding Group (OSG) for the foreseeable future.

Monday afternoon, the two jointly announced OSG was exercising options to extend charter agreements with the Norwegian tanker owner.

"Our decision resolves the uncertainty associated with approaching contract maturities," OSG chief executive Sam Norton said.

"The extension of charter agreements on all of the vessels provide for continuity of our existing tanker operations."

Charters for five of the vessels were extended for another three years and the remaining four for one-year terms, all nine starting this month.

A previously exercised option means OSG has 10 vessels from American Shipping Company. The charters include a profit sharing agreement.

AMSC chief executive Pal Lothe Magnussen said the deals ensures the company's stable cash flow and maintains its exposure to an improving Jones Act tanker market.