The government has sent a letter to the most influential media organisations, calling for submissions to provide public service broadcasting content alongside the BBC.

Today's letter, which is being sent to "organisations that believe they may have a role to play in the future architecture of PSB in the UK", calls for submissions by 6 March, with "proposals to inform the analysis and decision making phase" of the government's plan to establish a new commercially-funded PSB organisation, with Channel 4 at its heart.

The letter outlines three key points that any proposal submitted on "PSB2" should include. Interested parties are asked to give their views on any new governance structure necessary for the new PSB body, plus an outline of how an updated remit would include a core TV channel, multi-platform capability, news and current affairs, UK production, and possibly children's content.

Thirdly, the government is seeking feedback on a business model that has "scale, sustainability and flexibility" for the new PSB venture.

"Government believes that, in order to have the potential to play a credible role, an interested organisation should be of a sufficient size to invest either capital or assets at a significant level, and have a proven track record and profile in content production or broadcasting on an international scale," said the government in the letter.

Last month communications minister Stephen Carter's Digital Britain report recommended that a deal between Channel 4 and BBC Worldwide should be considered as the preferred option for funding the new PSB body.

However, the government has not ruled out wider options such as a merger between Channel 4 and Channel Five, or a partnership with other media companies.

The key, the government said, is to create a body that would have "public service at its heart, but with the freedom to develop flexible and innovative partnerships with the wider public and private sector".

The process for developing the PSB2 proposals will be coordinated by a project team drawn from the department of culture, media and sport, the shareholder executive within the department for business, enterprise and regulatory reform, and financial adviser UBS.

• To contact the MediaGuardian news desk email editor@mediatheguardian.com or phone 020 3353 3857. For all other inquiries please call the main Guardian switchboard on 020 3353 2000.

• If you are writing a comment for publication, please mark clearly "for publication".