On both days, Tharoor alleged that Narayan Singh was "repeatedly physically assaulted by one of your officers.

"Worse, that officer used the traumatic physical assault to try and intimidate Narayan into 'confessing' that he and I murdered my wife," the former central minister said.

Tharoor recalled that he expressed his concerns to Bassi over telephone Nov 8 night.

"As you graciously agreed, such conduct is completely unacceptable and illegal," Tharoor said in his letter. "It also amounts to the use of physical coercion in the attempt to frame an innocent man.