Philippines hero Manny Pacquiao has signed a deal to fight US star Floyd Mayweather on March 13, ESPN reported on Saturday, saying there will be a 50-50 split in what could be boxing's richest fight.

Undefeated Mayweather had agreed to terms for the bout but it was not certain he had signed a deal and there have been reports Pacquiao wanted minor changes that might need to be confirmed with the American's camp.

Mayweather, 40-0 with 25 knockouts, was regarded as the world's top pound-for-pound fighter before a 19-month layoff that ended last September.

Pacquiao, 50-3 with 38 knockouts, staked his claim to the pound-for-pound crown in Mayweather's absence by knocking out England's Ricky Hatton in the second round last May and stopping Miguel Cotto in the 12th last month.

Each fighter's side was seeking a 60-40 share of proceeds and for a time it appeared the only mega-fight on boxing's horizon might never be made because there was not enough money to go around.

Instead, the Pacquiao-Mayweather showdown appears set and could bring record profits to break the mark set by Mayweather's split-decision victory over Oscar de la Hoya in 2007.

Pacquiao will risk a lesser sanctioning body welterweight crown, with the fight will be staged at that class's 147-pound limit and each fighter can select the brand of eight-ounce gloves he desires, ESPN said.

The promotion, expected to carry Mayweather's name ahead of Pacquiao's but give Pac-Man's promoter Top Rank a higher billing over Golden Boy, is expected to be launched with a January news conference in New York.