By Karolos Grohmann

LONDON (Reuters) - A new long-term deal between the International Olympic Committee and the U.S. Olympic Committee will run to 2040 and will be beneficial for both sides, the IOC's marketing chief said on Tuesday.

The IOC ended years of dispute with the USOC in May over the Americans' large share of revenues from sponsorship and TV programs stemming from an agreement signed decades ago when almost all top Olympic sponsors were American companies.

The row over how to divide billions of dollars in TV rights and sponsorship had dragged on for long and left the USOC a virtual outcast within Olympic circles.

"This agreement is good for both parties, it is good for the IOC and the USOC as well," said Gerhard Heiberg. "The new agreement will unconditionally terminate in 2040. This is a long-term agreement."

The new deal foresees that the U.S. share from broadcasting rights will be reduced from 2021 onwards from just over 12 percent to seven percent, Heiberg told an IOC session.

The USOC's share from the IOC's top sponsorship program will be halved from 20 to 10 percent starting in 2021.

The IOC had long argued USOC's share was no longer representative of its sponsors as more companies from other parts of the world had joined.

Before the new deal the USOC had felt it was entitled to a larger share, claiming that it is American television rights and sponsors that keeps Olympic coffers flush with cash.

The acrimony escalated to the point that the USOC believes it was a key factor in New York's failed bid for the 2012 Summer Games and Chicago's defeat when Rio de Janiero was selected for the 2016 Olympics.

(Editing by Greg Stutchbury)