World champion Lewis Hamilton "stands with" US sports stars boycotting events to fight racism but does not think his missing a race would have an effect.

Basketball, baseball and football games have been postponed in the US after police shot Jacob Blake, a black man, seven times in the back on Sunday.

Hamilton said: "It's a shame that is what's needed over there to get a reaction. But that is in America and I don't know really if me doing anything here will particularly have any effect."

Sebastian Vettel said drivers' pre-race anti-racism protests would continue.

Hamilton, F1's only black driver, said in the build-up to this weekend's Belgian Grand Prix: "It's incredible what many out there in the States are doing within their sports, all the way down to the people who are hosting.

"So many people are standing with the players and really pushing for change.

"I haven't spoken to anyone about it but I am really proud of so many out there and I do stand unified with them.

"I don't really know how us not doing the race is a thing. But I will try and speak to F1 to see what else we can do to continue to raise awareness and help push.

"And as a sport we all need to be aligned and supporting one another, even though it is a different sport."

Hamilton has been at the forefront of F1's support for anti-racism and diversity this year, which has led to demonstrations by the drivers and the sport before every race.

Vettel, a director of the Grand Prix Drivers' Association, said all 20 F1 drivers were united in their desire to keep pressing the message home.

"We sent a strong message after the first event and our feeling was very clear that we wanted to continue sending that message," he said.

"It is one of those things that does not go away overnight.

"How long will we continue? There is no answer to that. It is important to keep sending the message and that's what we will continue to do."

The Ferrari driver added: "We know it is does not change things overnight and it is only a very small contribution, but hopefully everyone who tunes in and sees it gets the point and takes a little bit of that for the next steps he is facing in life.

"Because one thing is to take action in public but more importantly is how everyone is acting and confronting it once the cameras are off. That is true for us and it is true for everyone else."
Hamilton sees Verstappen as a threat

Hamilton has won four of the first six races this season and has opened a 37-point championship lead over Red Bull's Max Verstappen, with the Briton's Mercedes team-mate Valtteri Bottas a further six points adrift.

Hamilton said he saw Verstappen as a genuine threat in the championship.

"If you take away Max's DNF (retirement) in race one away, we would be very close in points," he said. "They have had very strong results. Maybe in qualifying we do have the edge. But in races we are a lot closer.

"We are not even halfway through the season. I absolutely keep my eye on them. They are absolutely still a title runner and we need to stay on our toes."
Memories of Hubert

This weekend's race is a year on from the death of Formula 2 driver Anthoine Hubert at last year's event.

On Thursday, Alpha Tauri driver Pierre Gasly, a childhood friend and rival of Hubert, lay flowers beside the track at the spot where Hubert was killed, the high-speed Raidillon left-hander, which is the final part of the infamous Eau Rouge swerves.

Ferrari's Charles Leclerc, winner in Belgium last year and another close friend of Hubert, said many drivers would be thinking of him this weekend.

"Last year was very difficult on the Saturday night," Leclerc said. "We all learned about Anthoine passing away and on the Sunday I spoke with Pierre. We were all good friends and Pierre said 'You have to win for Anthoine on Sunday'.

"I wanted to do that, too. It was very special but also very difficult. It was the first time I had experienced driving around the same track when you have lost someone close.

"Coming back doesn't change that but it doesn't change my targets for the weekend, which is to do the best I can in the car."

Ferrari, however, are expecting a difficult weekend, as a result of the lack of speed they have shown on the straights this year following a series of rule clarifications over the winter.