A probe panel looking into the crane mishap at a Delhi Metro site during debris clearance on Wednesday held the contractor Gammon India responsible saying "mismanagement and lack of professionalism" from its part resulted in the incident, a claim rejected by the firm.

"We have received the report on the snapping of cranes in Zamrudpur. It holds the contractor's mismanagement and non-professional approach as the reasons for the mishap," Delhi Metro chief E Sreedharan told reporters.

The DMRC has appointed B P Singh, an expert on cranes and ex-General Manager of NALCO, to inquire into the July 13 mishap when a crane toppled over and booms of two other cranes broke during site-clearing operations at Zamrudpur.

Sreedharan said Gammon India used four cranes at the same time, which was not the practice. "Two cranes should have been used instead of four. Once you use four and if one of them develops a snag, then everything goes wrong", he said.

"The report also said that the clearance of girder from the site should have been done in two stages. There is a sheer error in judgement. Fortunately, only four cranes were lost but it is a very major incident," he said adding Metro was "not very much" involved in debris clearance operations.

In a statement, Gammon India refuted the allegations and claimed that DMRC engineers were fully aware and involved in the operation and they did not receive any communication from the one-man committee set up by DMRC investigating the crane mishap.