The chief executive of BP tells Sky News he believes the massive Gulf of Mexico oil spill will end up having only a "very, very modest" environmental impact.

Experts had feared the Deepwater Horizon disaster could have led to one of the worst environmental catastrophes in U.S. history.

But the British oil giant has risked outrage along the Gulf Coast by predicting a far smaller impact.

"I think the environmental impact of this disaster is likely to have been very, very modest," Tony Hayward said. "It is impossible to say and we will mount, as part of the aftermath, a very detailed environmental assessment but everything we can see at the moment suggests that the overall environmental impact will be very, very modest."

Click here to see video of Tony Hayward's statement.

BP has begun capturing some of the leaking oil after inserting a suction tube into the fractured riser pipe on the seabed.

It is gathering up an estimated one fifth of the oil pumping out of the fractured well.

"Over the last 36 hours we have made a lot of progress on containment on the seabed," Hayward said. "We have a piece of technology engineering which we have developed and which is now allowing us to produce oil from the leak to the surface."

The BP chief spoke to Sky News after completing a visit to Florida where he handed over $25 million to pay for an advertising campaign for the state's tourism industry.

He appeared upbeat as he met teams at BP's vast crisis control center in Houston.

The center has been working around the clock for more than three weeks trying to identify solutions to the crisis.

The company believes the next stage of its response effort could see the leak sealed completely within seven to 10 days if all goes to plan.