The Tigers were relegated despite a record haul of 19 points

The Tigers, relegated last weekend, had lobbied other clubs in a bid to persuade the Rugby Football League to expand the league to 13 teams.

But a Castleford statement said: "We have accepted that there will be no reprieve on the basis of Super League expanding to 13 or 14 teams.

"We have agreed to the RFL's request to accept the current process."

Castleford could still stay up if the winners of Sunday's National League play-off between Whitehaven and Batley - neither of whom qualify for promotion - go on to win the Grand Final.

If Widnes or Hull KR win the National League finale, then Castleford's relegation will stand.

At present, the Tigers are planning to keep their full-time status next season even if they are out of the top flight.

The club believes that the game's promotion and relegation rules are flawed Castleford statement

And they hope to retain the services of coach Terry Matterson, who still has 12 months left on his contract and has asked for more time to consider his future.

Castleford claim that some other Super League teams had agreed to accept a reduced share of central funding in order to accommodate an extra team.

"The Tigers would like to thank, in particular, those Super League clubs that were prepared to accept reduced revenue distributions for the greater good of the game," the statement continued.

Castleford's relegation was confirmed after the loss to Wakefield last weekend and despite a haul of 19 points, six more than the previous best accrued by a relegated team.

Matterson (R) consoles Michael Shenton after the Wakefield loss

They went down as basement club Catalans Dragons are exempt from the drop for their first three years in the competition.

And the Tigers, who were only promoted last year, are angry that National League clubs have less time to prepare as promotion to Super League is not confirmed until the Grand Final in October.

"No other sport lays down such an insurmountable challenge," added the statement.

"Only 10 of the 17 players selected at Wakefield made it to the club's pre-season camp in Tenerife, four weeks before the club's opening game against Hull.

"This limited preparation was the unsatisfactory and unfair foundation for the Tigers entering the most competitive Super League ever.

"The dice are impossibly stacked. The club believes that the game's promotion and relegation rules are flawed."

The League have plans to move to a franchise system and a 14-team competition by 2009.