New Orleans Saints coach Sean Payton says improvements must be made before another NFL game is played in London.

The Saints beat the San Diego Chargers 37-32 at Wembley on Sunday in the second of the NFL's International Series of games here.

Having been largely upbeat about the trip following the game, Payton admitted to several concerns once back in Louisiana.

"It'd be hard for me to say it's a great experience, a great thing for your club," Payton said.

"Logistically, I think it's hard to take two teams over there and play a game during the regular season like this. The travel, the transportation ... those aren't club issues but league issues. They have a lot of work to do to figure this thing out."

Payton praised the "fantastic" crowd but was less positive about the Wembley surface, which also came in for heavy criticism in last year's mudbath between the New York Giants and Miami Dolphins.

"I thought the field conditions were poor, real poor," he said.