The new deal is to run over a four-year period and follows the launch of the AOL Broadband service in June.
Karen Thomson, chief executive of AOL UK, said: "This agreement will give AOL the widest coverage of any broadband service provider in the UK and help us to build a leadership position in the high-speed market."
It is seen as an important move for AOL because its UK broadband service is only currently available via BT's ADSL network. AOL says the 7.2m broadband-enabled households on NTL's network, combined with AOL's existing coverage, represents the largest potential customer base of any UK online service provider.
For NTL, the move takes its wholesale internet strategy forward and the deal with AOL, it says, marks the launch of the first wholesale cable broadband proposition for a UK online service provider.
Paul Rusby, director of wholesale internet services at NTL Business, said: "NTL Business has established its leadership in the wholesale internet solutions market by adopting a partnership approach with leading providers such as Virgin.net and Tesco."
The two also announced that they had extended their existing strategic agreement, which sees NTL Business continue to provide a managed flat-rate network for AOL dial-up customers.
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