Bilateral series outside iconic ones like the Ashes and big-ticket tours involving India could be endangered in the future if they are not properly nurtured and marketed.

The alert has come from ICC chief executive David Richardson, who says the success of domestic Twenty20 leagues like the IPL, Big Bash and the growing Caribbean Premier League have made them more attractive to cricket fans and broadcasters.

To arrest the decline of bilateral series, cricket's administrators are discussing the creation of qualifying leagues for both Test and ODI cricket as a possible solution.

"Apart from series such as the Ashes - which has an iconic, traditional status - and series between India and the top Full Members, many bilateral series are perceived as having little relevance," Richardson told ESPNcricinfo in London.

"Attendances in most series, especially for Test cricket, have fallen and the revenues generated from these series are not growing."

Richardson said the issue was once again high on the agenda at the ICC annual conference in Barbados in June and would take precedence at the next ICC Board meeting in October.

"The international cricket landscape has changed over the years and even more significantly in recent times with the advent and success of domestic Twenty20 leagues such as the IPL, the Big Bash and the CPL.

These events are attracting widespread support from fans and hence the interest of broadcasters, sponsors and other commercial partners.

"Similarly the interest in and value of ICC events such as the World Cup, the Champions Trophy and World Twenty20 has grown significantly over the last eight years or so. The increase in interest in ICC events and domestic Twenty20 leagues effectively provides competition for the interest in bilateral international cricket series (FTP series)."

How can the ICC enhance the appeal of bilateral series that are part of the FTP and an important source of revenue for the Full Members?

Providing context to these contests has been the popular response in the past, and Richardson offered the same solution to begin with. He also felt that sometimes countries were responsible for their own plight.

"How can we grow interest in bilateral series - bigger crowds, more people watching on television, following the series on their phones, tablets and computers? For this to happen bilateral series need greater context, a clear narrative, improved marketing and a more certain and coordinated schedule," Richardson said.

"What's the use of scheduling a series in the monsoon season or how can you expect to grow the fan base or attract attendances if series are scheduled or changed at the last minute?"

To make bilateral series more relevant, Richardson said countries needed to opt a less-is-more formula. Instead of an irrelevant seven or five-match series, Richardson suggested a better substitute to be a tri-series scheduled at an opportune time.

Richardson revealed a possible solution the administrators were thinking about was creating qualifying leagues for both Test and ODIs, an idea that had the support of all the powerful members of the ICC Board.

"Scheduling more tri-series, creating a brand around the FTP and around individual series, creating a fresh brand for the ODI format itself (World Cup Cricket for example, as Wally Edwards is proposing), creation of Test or ODI World Cup Qualifying leagues.

These are all ideas that need to be considered and discussed. They have been mooted before, but now with the involvement of Srinivasan as Chairman, the BCCI, ECB, CA and the other Members, these issues are being seriously looked at.

"We are just in discussions at the moment. Michael Holding has spoken about a Test league of two divisions, others have previously suggested a six-and-four teams format.

But first the principles and then the detail needs to be debated and agreed. I think it is achievable if all the Full Members think it is worthwhile and want it to happen."

According to Richardson, any such league system would be independent of the ICC ranking, similar to the qualification leagues in football.

"The debate on leagues is still in the drawing board phase, but even if leagues were introduced, the rankings would still coexist. The ICC rankings will always be there. Take international football, for example, they have qualifying leagues for the FIFA World Cup and Continental tournaments, separate to the world rankings."