They will have 21 days to answer. Depending upon the answer, we will take action on them.'

He went a step further and said: 'For now the right thing is to pack the Gammon away but if it is done then there will be delay of six to eight months which we can not afford as then we will get delayed with the Commonwealth Games deadline.

'Gammon India is very important for us. They are involved in five major projects in Phase II. If you take them away, the projects will get delayed by six to eight months. We need Gammon India. Unfortunately, we don't have many big construction companies,' he told reporters here, adding that blacklisting Gammon 'at this point of time means floating tenders once again'.

To ensure safety, DMRC will ask Gammon to better its quality and safety assurance. 'We are going to ensure quality assurance and safety assurance one level more than what it is today.'

Sreedharan assured that Metro structures are completely safe and the checks being carried out now will remove even small deficiencies, if any.

'The DMRC has decided not to depend entirely on its design office when it comes to the designs. General consultants or an independent design office will check the designs first and then pass it on to the (DMRC) design office. So there will be a double check,' the Metro chief said.

'There will be two-tier checking mechanism for designs'.

The Metro man also said that all the cantilevers - 87 in the phase two lines and 38 in the airport line - will be independently assessed. Talking about the cracks in 18 piers, Sreedharan said DMRC is employing a London-based consultant to asses them. 'The construction over these 18 piers are over. We will carry out a load test and give 25 percent more load than a real life situation.'

Earlier in the day, Urban Development Minister S. Jaipal Reddy informed the Lok Sabha that a probe panel, headed by IIT-Delhi professor A.K. Nagpal, found 'serious deficiency in the design of the cantilever arm and the concrete (used in the construction) not having the adequate strength'.

However, Sreedharan said that based on tests carried out on cores taken from the pier and cantilever, 'it has found that the concrete fails to meet the strength criterion by a wide margin'.