The discussions are being backed by France Telecom, NTL's largest investor with a 25% stake in the UK cable operator. The French company is said to be keen to bring aboard a new investor to help share the burden.
However, the current negotiations are thought to rely on NTL restructuring its £12bn debt.
The talks are believed to have begun last month and a decision on whether to bring in one of the media companies is thought to be two or three months away.
The parties have yet to decide whether a new investor would buy equity or debt in the company. Meanwhile, NTL is set to deliver a revised business plan and 2002 financial projections that will involve cutting capital and operational expenditure.
If Liberty took a stake, it would follow the recent rescue of Dutch-based pan-European cable company UPC. Liberty Media boss John Malone is understood to be on a cable-buying spree across Europe, where he hopes to mirror his success in the US.
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