Two private cellular operators in Delhi -- AirTel and Hutchison-Essar – complained on Friday of disruption in calls from cell-to-fixed line phones and vice versa even as state owned Mahanagar Telephone Nigam Ltd dismissed the industry's apprehensions that it was blocking calls on selective basis.

According to Harit Nagpal, head (marketing) of Hutchison, company's call centres were flooded with complaints from their subscribers that their calls were not getting through fixed line telephones.

When contacted MTNL CMD Narinder Sharma told PTI, "We are looking into the system. There might be overloading due to increased traffic flow on account of Tata Teleservices trying to route their WLL(M) calls through our network."

Asked whether MTNL has started blocking cellular operators' calls, Sharma said, "no" and added that officials were looking into the system to see if there was any technical snag.

AirTel officials also complained that their subscribers were unable to receive or make calls to fixed line phones.

Third private cellular operators in Delhi, Idea, said there was no such problem to their customers.