They have also been barred from raising money from the public till further directions.
The company's present directors who have been barred are Arvind Gupta, Yogesh Ghisumal Gemawat, Girishchandra Mukundram Baluni, Sanjay Gupta, Kamlendra Joshi, Manoj Singhal and Suresh Kumar as also a past director Nimain Charan Biswal.
Sebi found that the company violated Companies Act provisions while raising money through NCDs issue.
In its 14-page order, the regulator said NTL and its executives are "restrained from accessing the securities market and further prohibited from buying, selling or otherwise dealing in the securities market, either directly or indirectly, till further directions".
The matter was referred to Sebi by the Corporate Affairs Ministry in late 2014 after the latter received a complaint regarding mobilisation of funds by NLT.