Amidst the rift over setting up of a National Investment Board (NIB) to fast-track clearances to mega-infrastructure projects, Environment Minister Jayanthi Natarajan Monday said she will take up her reservations on it with Prime Minister Manmohan Singh.

"I will speak to the prime minister about the reservations on the issue. Whatever I have to say, I will say it in the cabinet and to the prime minister. My mandate is to protect the interest of the environment," Natarajan told reporters.

Natarajan, in a letter to prime minister Oct 9, said that Finance Minister P. Chidambaram's move to set up an NIB to fast-track clearances of infrastructure projects above Rs.1,000 crore, is "unacceptable".

The NIB would ensure that major projects would be cleared without any delays by setting time limits for clearances and if it finds that the environment ministry has failed, it would take over cases of clearances.

The green ministry has been held responsible by the industry and many other ministries like coal and highways for delaying infrastructure projects, thus hampering the country's growth.

The charge has been refuted by the environment minister, who said  it has cleared power projects way above those needed to meet electricity demands for the next few years.

Natarajan has also got support from Tribal Affairs Minister V. Kishore Chandra Deo, who has written to her saying that no clearance should be given to projects that violate the law.