Two people who were detained in connection with the July 11 serial train blasts in Mumbai have admitted to having links with international terror groups.

The revelations came during scientific tests carried out on them, Anti-Terrorism Squad sources said on Wednesday.

The brothers, Muzamil Sheikh and Faisal Sheikh, arrested after the July 11 bombings have admitted to having links with international terror groups during the scientific tests carried out on them at Bangalore-based forensic science laboratory, ATS said in a remand application.

The agency was seeking an extension of the custody of the two before a local court.

ATS chief K P Raguvanshi said, "I cannot give more information. We have said whatever we had to in the remand application." Meanwhile, Deputy Chief Minister R R Patil said the investigations into the July 11 train blasts are at a "concrete stage" and the perpetrators of the crime will be brought to book in eight to 10 days.