Expressing his displeasure over repeated attacks on CAG by a section of UPA members during Public Accounts Committee meetings on 2G spectrum loss figures, PAC chairman Murli Manohar Joshi has shot off a strongly-worded letter to finance minister Pranab Mukherjee on the issue.

In his letter, Joshi is understood to have questioned the way CAG Vinod Rai and his officials were attacked by some Congress members on the issue of presumptive loss of Rs 1.76 lakh crore.

He is said to have enclosed a copy of the remarks of Congress member Sanjay Nirupam who had questioned the loss figure and wondered why Rai had overruled his junior RP Singh who had projected a lesser figure of Rs 2645 crore loss.

Joshi is learnt to have said that while ministers boast of institutions like CAG in their interactions abroad, the auditor is attacked by members of the ruling alliance in the country.

The letter was sent earlier this week, the sources said.

He also raised the issue of CAG Rai and Singh not being allowed to speak when they were called to clear the air over the presumptive loss figures before the PAC a few days ago.

To highlight the importance of CAG, Joshi is also learnt to have recalled the recent statement of Rural Development Minister Jairam Ramesh to get UPA's flagship MNREGA scheme audited by CAG.