Planning Commission deputy chairman Montek Singh Ahluwalia on Sunday said a government cannot be run only by those who know how to build roads, rebuffing transport minister Kamal Nath's charge that the plan panel was an "armchair advisor".

"My view is that you cannot run a government only with people who know how to build roads. You have to give them a set of rules..." Ahluwalia told CNN-IBN.

Nath had hit out at the Planning Commission on July 5, describing it as an "armchair" advisor oblivious to the ground realities of building roads.

"Producing a book is one thing and producing a road is another thing," he had said at a Planning Commission programme.

While Ahluwalia agreed that "building roads is certainly different from writing guidelines," he said, "we are not an implementing body. Equally, it does not mean that you (ministries) don't need advise. I mean accountants are not people who build roads but you cannot build roads without having decent accounts."

He said that different arms of the government play different roles.

Ahluwalia also rebutted Nath's charges that the plan panel was not allowing his ministry to achieve the 20 km-a-day road-building target.

"I don't think that is at all correct," Ahluwalia said, adding that when targets are set, "you have to relate that target to the funding that is available."

One of the principal roles of the Planning Commission is to scale down the demands of ministries, which are typically 100 per cent more than the money available, he said.

On Nath's remarks that the world class terminal at Delhi airport would not have been possible, had the Planning Commission been involved in it, Ahluwalia said the plan panel had a role, but was limited to selection of the operator (GMR Group).

"It was a public-private-partnership and the government's involvement was prior to the selection of the partner. It is absolutely true that once selected we didn't get involved.