Wales's four regions will join Premiership Rugby and create an Anglo-Welsh league for a minimum of five years if agreement on the future of the Heineken Cup is not reached by the end of January.

The regions met in Cardiff on Tuesday morning having been given a deadline of midnight by the Welsh Rugby Union (WRU) to continue a participation agreement that would tie them to the governing body for the next five seasons without an increase in funding in real terms.

The regions said that, as there will be no Heineken Cup next season as things stand while Italy has yet to commit to remaining in the RaboDirect Pro 12, they faced losing 10 fixtures and more than half the income they receive from tournaments. The unanimous decision was that continuing the agreement would bankrupt them.

"The WRU do not and could not run their business in such circumstances and neither can the regions," said the four in a statement that was issued shortly after office hours at 5pm, having waited to see if the union would make a late approach for talks.

"The WRU hold full responsibility under the participation agreement for the competition platform and television rights of the regions and it is astonishing that they have put the four businesses in this position as a result of failing to fulfil their obligations under the agreement, despite having almost two years to resolve the issues."

The regions said they remained committed to working with the WRU to secure a sustainable and competitive future for professional rugby in Wales, pointing out that clubs in England and France are increasing their spending after securing lucrative deals.

"We have had no choice but to consider every alternative to secure a truly sustainable future for regional rugby in Wales," the statement continued. "Therefore we reaffirm our commitment to the Rugby Champions Cup under the aegis of Six Nations, which will generate a guaranteed £12m additional funding across the four regions over the next three years and help reduce the funding gap with the French, English, Irish and Scottish clubs.

"A solution must be reached by the end of January 2014. Should this not be possible, the regions will have no choice but to pursue further competition options immediately."

The Rugby Champions Cup was the tournament announced by the English and French clubs in the autumn as a replacement for the Heineken Cup. It was to be run by clubs but the French sides pulled out under pressure fromtheir union, whose plan for a five-nation tournament without the English next season collapsed at an acrimonious meeting in Dublin.

The meeting was held under the auspices of the current tournament organisers, European Rugby Cup Ltd (ERC). The president of the French Rugby Federation, Pierre Camou, walked out when he failed to persuade a majority of the other unions that the Heineken Cup should be controlled by Fira, the organisation that represents the smaller unions in Europe.

The WRU protested when ERC's independent mediator, Graeme Mew, revealed he had spoken to the Welsh regions the day before the meeting and it will take a remarkable swing to achieve consensus about governance within a month. Telephone conversations continued over the holiday period, but if the Celtic unions maintain their opposition to clubs running the commercial side of the tournament, talks between the Welsh regions and English clubs over a 16-team Anglo-Welsh league are so far advanced it would take little more time to set up.

The WRU issued a statement that said it was confident professional teams from Wales would take part in "sanctioned" league and cup competitions, that it envisaged the Heineken Cup continuing under ERC's banner and that it supported the International Rugby Board's regulation that stipulated cross-border tournaments could only take place with the consent of the relevant unions.

The WRU's board meets on Thursday when it will consider its options, including offering central contracts to players such as Leigh Halfpenny, whose regional deal ends this summer, and creating new professional teams to take the place of the regions.

The statement pointed out that the regions had chosen, from next season, not to maintain their contractual right to be the WRU's nominated teams in sanctioned competitions and the battle looks destined for court.