BT will give altnets a three-month deadline to bring their 'whereabouts' compliance rate up to 90 per cent, according to a Daily Telegraph report.
The company will write to providers this week, telling them to improve their compliance with rules that require them to provide information about where and when they plan to access its ducts and poles.
Firms that fail to meet the deadline will be asked to hand over formal improvement plans. If they are still non-compliant by the end of the year, they could be blocked from accessing BT's network in certain areas.
Whereabouts is the process where companies register with Openreach whenever they access its network.
In the event of any damage caused to its infrastructure, failure to inform Openreach where they access it during network construction may result in an inability to determine where and when it happened and whose responsibility it was.
Altnets have been rolling out their networks at a rapid pace, but their expansion plans could be significantly delayed if they are shut out of BT's network.
Openreach said it would start instigating a contractual breach for providers working in the network with no whereabouts information from February. Its latest figures show compliance rates are still low, with the industry average standing at just 63 per cent. Compliance by some firms is as low as 20 per cent.
Altnets were given until 1 April to provide alternative approaches to whereabouts compliance.
Katie Milligan, at Openreach, said: "We're continuing to work closely with the industry, the OTA [Office of the Telecoms Adjudicator] and Ofcom to make sure that any work happening on our network is recorded properly, and completed safely and securely."