The National Basketball Association and player's union donated $1 million to the Texas flood disaster relief effort on Tuesday, adding to the millions already raised across the US sports world since the deadly weather system battered the region.

In a join statement, the NBA and NBA Players Association (NBAPA) said it was donating the cash to "bring relief to those impacted."

"Our thought are with the city of Houston and all those affected by flooding in the aftermath of Hurricane Harvey," the statement said.

The statement came after news reports said that Houston Rockets owner Leslie Alexander had donated $10 million to the Hurricane Harvey Relief Fund.

"Our hearts are heavy seeing the devastation that so many of our friends, family and neighbors are experiencing," the Rockets said in a statement. "... Please stay safe, Houston."

Rockets point guard Chris Paul made a separate donation of $50,000 to a fund created by NFL star J.J. Watt, who plays for the Houston Texans.

Watt's fund had raised $500,000 in a 24-hour period and has now surged past $4 million, Watt said on Twitter on Tuesday.

The defensive star said the fundraising drive on the YouCaring.com website was now targeting a total of $5 million.

"Forty-eight hours ago we set out to raise 200 grand. And now we're over $4 million...I can't say thank you enough," Watt said.

Donors to the fund included Tennessee Titans owner Amy Adams Strunk, who made a million dollar donation, the team said.

"The flooding and devastation to the Houston area has been painful to watch," Strunk said in a statement.

"As a native to the area, I have been so encouraged to see how the locals and the nation as a whole have come together to help one another.

"The NFL, at the end of the day, is a family that helps one another in times of need."

Meanwhile Texans owner Bob McNair had pledged a $1 million donation to a separate flood relief fund, which the NFL Foundation vowed to match.

Also on Tuesday, the Dallas Cowboys said that all proceeds from their NFL pre-season game against Watt and the Texans at AT&T Stadium on Thursday would go towards the disaster relief fund.

Robert Kraft, the billionaire owner of the New England Patriots -- who won the Super Bowl in Houston in February -- pledged to match $1 million in donations to the American Red Cross relief fund for victims of Harvey.

Source: AFP