Overseas Shipholding Group (OSG) will hang on to a quartet of American Shipping Company tankers for another three years.

OSG, the New York-listed Jones Act player, said the deals tack another three years onto the back of charters ending next December, keeping them under control until December 2023.

"The decision to further extend the maturities of each of the four vessels underscores our confidence that the continuing move towards balance in the Jones Act tanker market is an opportunity to serve our core customers in a rate environment that will provide attractive returns over time," chief executive Sam Norton said in a statement.