According to a report published Sunday in the Financial Times, bids for the company are due on Thursday.
Channel 5 owner Richard Desmond (pictured), a British publishing mogul, hopes to fetch more than $1 billion for the asset, which he bought in 2010 for about $173 million.
The FT reported that Discovery is considering a joint bid with 21st Century Fox-controlled British Sky Broadcasting.
NBCUniversal has been actively expanding its international holdings in recent years under parent company Comcast Corp. Saban Capital, parent company of Univision Communications, is a frequent contender when big media assets come on the block.
Investment bank Barclays is handling the Channel 5 sale for Desmond.