The off-season has seemingly done little to ease the bad blood between Red Bull and Mercedes heading into the new Formula 1 year.

After the most controversial and dramatic season in more than a decade, Red Bull's reigning world champion and team principal both took swipes at their Mercedes rivals ahead of this weekend's Bahrain Grand Prix.

Team boss Christian Horner accused Mercedes' Toto Wolff of pressuring motorsport's governing body to sack last season's race director Michael Masi rather than admit his own mistakes.

Masi played a key role in the controversy which saw Red Bull's Max Verstappen beat Lewis Hamilton to the 2021 drivers' championship on the last lap of the final race.

'I felt what was going on behind the scenes over the Christmas period was a bit underhand," Horner told the UK's Daily Mail. 

"The reality was Michael Masi didn't break their own rules. Mercedes had all the same strategic options available that we did, they made a mistake strategically not pitting Lewis.

Wolff and Hamilton boycotted the F1 prize ceremony in Paris at the end of last season, another action Horner said was aimed at trying to undermine Verstappen's championship win.

It is not only Horner who has questioned Mercedes heading into the start of the new season.

Verstappen rubbished claims made by Hamilton last weekend that Mercedes would not be able to compete for victories at the start of 2022. 

F1 has gone through one of the largest regulation overhauls in its history, with this year's cars starkly different to last season's.

Changes to the aerodynamics and the tyres mean teams have taken very different approaches to the new machines. 

"At the moment, I don't think we will be competing for wins," Hamilton said after the final three-day test in Bahrain last weekend.

"I think Ferrari look to be the quickest, perhaps Red Bull and then maybe us or McLaren, I don't know. 

"But we are currently not at the top."

Verstappen told Autosport it was common for Mercedes to downplay their abilities despite winning the last eight constructors' championships.

"If someone is doing well or a team that everyone expects to do well, then it's, 'Oh no, we're definitely not the favourite,'" Verstappen said.

"And then a week later, when things do go well, all of a sudden it's, 'Oh no, but we turned it around completely within a week. Not normal, unbelievable work. Thanks to all people in the factory.'"

The Bahrain Grand Prix will be held on Monday, March 21, at 2am AEDT.