Seven-time Formula One champion Lewis Hamilton protested the FIA's crackdown on body piercings by showing up at the Miami Grand Prix wearing every piece of jewellery he could fit on his body and suggesting he was willing to sit out races over the issue.

Hamilton arrived in the paddock wearing an all-denim outfit with several open buttons on his long-sleeved shirt that showed at least four stacked necklaces. Hamilton was later seen wearing at least three watches and with four rings on each hand. He also has earrings and a nose ring.

"I couldn't get any more jewellery on today," he said.

The FIA on Friday tightened its ban on non-regulatory underwear and body piercings when new race director Niels Wittich issued a bulletin that makes the rule part of official scrutineering, meaning such choices are subject to review by race officials.

Four-time champion Sebastian Vettel said he thought FIA was being petty and wondered if the rule was aimed at Hamilton, the 37-year-old Mercedes driver from Britain.

"I think it is a bit unnecessary to blow this topic up and probably at this stage is more of a personal thing, I feel a particular way targeted to Lewis," Vettel said. "In a way, there's a concern for safety, obviously if you have stuff and the car does catch fire. To some degrees, there is personal freedom and we are old enough to make our own choices."

Hamilton said when he is in the car "I only have my earrings and my nose ring, which I can't remove."

Hamilton said he sent new FIA President Mohammed Ben Sulayem a message before arriving at the track noting the jewellery fight seemed silly and that "I don't want to fight with you guys, ever." But also sounded prepared to hold his ground.

"If they stop me, then so be it," Hamilton said. "We've got spare drivers ready and prepped for weekends. There's lots of things going on in the city, anyway, so I'll be good either way."

Not long after that, Hamilton was seen in Mercedes' hospitality area wearing only one watch and one ring on his arm. By the time he took to the track for first practice, Mercedes had submitted the required document to FIA that declared Hamilton had removed all the jewellery he could. He's been given a temporary exemption on his piercings.

The governing body for Formula One said the primary issue is safety. It said drivers may be subjected to checks before competition because "the wearing of jewellery underneath the required flameproof clothing can reduce the protection afforded by this equipment."

"Metallic objects, such as jewellery in contact with the skin can reduce heat transmission protection and thus may increase the risk of burn injuries in the event of a fire," the FIA wrote. "The wearing of jewellery during the competition can hinder both medical interventions as well as subsequent diagnosis and treatment should it be required following an accident."

The FIA said jewellery can snag during emergency removal from a car, and can also complicate or delay medical imaging.

"In the worst case, the presence of jewellery during imaging may cause further injury," the FIA wrote. "Jewellery in and/or around the airway can pose specific additional risks should it become dislodged during an accident and either ingested or inhaled."

Hamilton has been pushing back since the FIA first announced a potential clampdown and said Friday he would sign a waiver assuming all responsibility. He said he has worn his bling while competing for 16 years in F1 without an issue, and also undergone numerous medical imaging sessions also while wearing his jewellery.

"It's platinum that I have, so it's not magnetic. It's never been a safety issue in the past," Hamilton said. "In 16 years, I've had so many MRI scans and not had to take out the platinum because it's not been an easy.: