Channel 4's chief executive Andy Duncan

The broadcaster is predicting a deficit of �100m in the next decade with the advent of multi-channel broadcasting.

Public funding could help the channel pay for non-programming costs such as transmission and distribution.

Channel 4's chief executive Andy Duncan said the BBC, ITV and Five are already cushioned from the effects of the move to digital, due to take place in 2012.

"The BBC has guaranteed funding from the licence fee. ITV has had a merger and will have a reduced public service broadcasting (PSB) contribution. Five also has a reduced PSB contribution, and will actually do better after switchover," he said.

External support

"Channel 4 is unique in being exposed to the pressures of the next five years," Mr Duncan added. "We're arguing for a mechanism to be put in place now."

Mr Duncan has submitted the proposals to broadcasting regulator Ofcom, which is conducting a review of public service television.

He said Channel 4 would need "a limited but appropriate amount of external support" in addition to its existing commercial income.

The broadcaster's submission also proposes that the BBC should pay for any additional costs it incurs during the digital switchover.

Banzai is one of Channel 4's more quirky offerings

Collaboration with the BBC in areas such as new media, education and tie-ups including international distribution are also outlined in the document.

The BBC's input is seen as "going much of the way to clearing the funding gap" in Channel 4's proposals.

Channel 4 is owned by the government, but makes its money from advertising and other commercial ventures.

Increased competition from other digital TV services could hit Channel 4's income.

It was considering a merger with Five, but talks were called off due to the complexity of the deal and lack of benefits.