Phil Mickelson and other world stars who have talked of possibly joining the European Tour may be forced into a rethink after it was decided tonight to up the minimum number of events required for membership from 11 to 12 - and to stipulate that at least two of them must be played in continental Europe.

The circuit launches its new-look ’Race for Dubai’ in just over a month, culminating in the world’s richest event in the emirate next November.

That tournament, the Dubai World Championship, is open only to the leading 60 players on the Order of Merit and Mickelson is among a number of US Tour-based players who have been considering taking up membership.

But after the meeting of the players’ committee in St Andrews tonight, Tour chief executive George O’Grady said: “It was a very positive discussion by the committee, who reviewed all aspects of the Tour and took into account the current economic situation.

“They felt this was a correct way to recognise the support of the founding body of the European Tour in Europe.

“It is a stepping stone and they will continue to review the situation on an annual basis.”

Committee chairman Thomas Bjorn added: “Over the years the seasons have been extended so much and we also think that with a 13-month season coming up, it is reasonable to put the number up by one.

“It is not a big ask to play 12 events, especially when a lot of those guys in question (who may want to join the European Tour) play four majors and three World Golf Championship events anyway.

“It was never a big ask, it was just time to change.”

Asked whether a larger minimum number of tournaments was considered, he stated: “No, 12 was always the preferred number. But we will keep it under review.”

The stipulation of two events in Europe comes after a season when many of the tournaments there have suffered from weakened fields.