Lewis Hamilton’s failure to put pen-to-paper on a new Mercedes contract is due to the “grotesque” amount of money involved, rival team boss Christian Horner has claimed.

The Briton, 33, is yet to sign on the dotted line of a new deal estimated to be worth up to £40million-a-year which is proving an unwelcome distraction for Mercedes.

Hamilton and Mercedes claimed at their Silverstone car launch back in February that his contract extension was likely to be rubber-stamped before the season-opening race in Melbourne.

Lewis Hamilton File Photo
Lewis Hamilton has yet to sign a new deal with Mercedes (Tim Goode/PA).

But more than three months later, they appear no closer to striking an announcement – with the driver stating this week that he is not in a rush to get the deal over the line.

Mercedes boss Toto Wolff emphasised again in Monaco that he is entirely confident Hamilton will extend his stay beyond the end of this season.

“We haven’t set a fixed date where we want to announce, but I can tell you that I don’t see a reason why this shouldn’t be happening,” Wolff said on Thursday.

2017 British Grand Prix – Race Day – Silverstone Circuit
Mercedes’ Toto Wolff is not worried Lewis Hamilton has yet to extend his time with the team (David Davies/PA).

“This is a work in progress and we see no hurry to pressurise each other into signing a document that will eventually anyway happen.

“We’ve had very good conversations and there is no desire for him to leave the team, and we have no desire for us to lose him.”

However, Horner – whose Red Bull drivers set the pace in both practice sessions for Sunday’s Monaco Grand Prix – believes cash is the contributing factor to the ongoing hold-up.

2017 British Grand Prix – Race Day – Silverstone Circuit
Red Bull Principal Christian Horner has offered his thoughts on the Lewis Hamilton contract situation (Tim Goode/PA).

“I imagine that a delay can only involve money,” Horner, the Red Bull team principal, said.

“I should think it is such a grotesque amount of money that Toto’s talking
about it is probably what’s making his and [Mercedes’ non-executive chairman] Niki Lauda’s eyes water at the moment.

“Lewis has got an expensive lifestyle. He is a four-time world champion and I doubt he is cheap.”

2018/19 Formula One Season Package
Lewis Hamilton is a four-time world champion (Tim Goode/PA).

Hamilton’s Mercedes team arrived at the principality fearing they would be playing catch-up to both Ferrari and Red Bull – and so it proved in practice on Thursday.

While Daniel Ricciardo completed a practice double to cement Red Bull’s tag as the pre-race favourites, Hamilton, who holds a 17-point championship lead, could manage only fourth as he finished more than half-a-second off the pace.

Monaco Grand Prix – Race Day – Circuit de Monaco
Monaco’s tight layout has not been kind to Mercedes in recent years (Daviid Davies/PA).

Mercedes have struggled at the slow-speed Monte Carlo street circuit in recent years – and Hamilton’s team-mate Valtteri Bottas was further back in sixth.

Ferrari notoriously keep a little in reserve in practice. Vettel was 0.572 seconds adrift of Ricciardo’s best effort, but it is Red Bull who will head into the remainder of the weekend confident that they can secure their first pole position since Ricciardo stormed to the front here two years ago.

2018/19 Formula One Season Package
Daniel Ricciardo can impress for Red Bull (Tim Goode/PA).

A cautious Horner added:  “Both drivers seem reasonably comfortable in the car but as we’ve seen Saturday has been our weakness throughout the season.

“We’ve always had a strong race car, but Saturday is where we’ve tended to struggle, at the business end of qualifying.

“Hopefully with the shorter straights here and with this circuit layout, it offers us our best qualifying chance of the season.”