NTL is withholding £67 million sterling due in interest payments on three US bonds.
But the company, whose debts total £12 billion, said it has enough funds to meet the interest payments. It said the decision to withhold them was made at the request of an unofficial committee of the company's bondholders.
The interest payments are about 50 per cent of the face value of outstanding publicly traded bonds of NTL and its subsidiaries.
NTL says a decision on whether to make the payments will be made in the 30-day grace period. It expects to receive around £209 million soon from the sale of its Australian broadband business.
Analysts believe NTL is close to reaching an agreement with its banks and bondholders over a deal that would see it accept new shares for writing off around £8 billion of debt.
This is expected to trigger a pre-arranged, temporary Chapter 11 bankruptcy filing, designed to give NTL three months in which to finalise a deal with creditors.
Chapter 11 would protect NTL from its creditors and enable day-to-day operations to continue as normal.
Analysts and industry sources say NTL is also in talks with potential strategic investors, including AOL Time Warner and Liberty Media.