The likes of O'Driscoll will miss the start of the league

The Irish Rugby Football Union insist the players from their summer tour of South Africa must complete a 10-week pre-season conditioning programme.

The move has angered Leinster and Munster, the most-affected sides who will lose a total of 19 players.

The news will also come as a blow to Welsh and Scottish teams, who will have problems marketing the devalued ties.

I think it's unfair on the competition, unfair on the supporters and unfair on the sponsors Leinster chief executive Mick Dawson

Munster travel to St Helen's to face the Ospreys in the league's opening fixture on 3 September, with Leinster welcoming the Blues on 5 September.

"We want to have a serious Celtic League, it's our bread and butter competition and I don't think we should be devaluing it," Leinster chief executive Mick Dawson told the Western Mail.

"I think it's unfair on the competition, unfair on the supporters and unfair on the sponsors."

The Irish move has also angered Llanelli Scarlets chief executive Stuart Gallacher.

"We are never going to get the league up to Zurich Premiership standard while the Irish refuse to commit to it in the same way as the Welsh and the Scots," he said.

"Their star names are probably only going to be playing in half the league games, so Leinster and Munster will be loathe to agree to qualification for the Heineken Cup being based on the Celtic League.

"Until we get that, it's not going to be a fully blown, meaningful competition."

Sadly the Celtic League is being sabotaged by the Irish From Dave Row Join the Scrum V debate

The IRFU is looking at ways of reducing the number of games its top stars play, but last month rejected claims a deal has been agreed which means the likes of Brian O'Driscoll are prevented from playing in Celtic League away matches.

"That is 150% untrue," IRFU spokesman John Redmond told BBC Sport.

Redmond revealed that Irish officials would prefer their top players to feature in just 30 matches per season rather than the maximum 42.