Amid the row over the installation of statue in the Delhi, the Congress backed National Student Union of India (NSUI) has blackened the bust of Veer Savarkar and garlanded the busts of Bhagat Singh and Netaji Subhash Chandra Bose installed by the Akhil Bhartiya Vidyarti Parishad (ABVP) led Delhi University Students' Union (DUSU) at Delhi University's Art Faculty.

The bust was installed by the DUSU president Shakti Singh on Tuesday, who was also earlier demanded to rename the DUSU office by Veer Savarkar.

Crticising the move of ABVP, the leader of NSUI said, "Savarkar cannot be kept on the same pedestal as that of Bose and Singh". About 20 NSUI activists blackened the bust of Savarkar and offered a shoe chain on the mid night of Thursday. They also raised slogans Bhagat Singh and Netaji amar rahe (long live).

"How could they have put the bust of Savarkar alongside Netaji and Bhagat Singh, that too overnight? We had to take matter in our hands. The university administration has been silent about the issue. The varsity is working at the behest of ABVP, the child unit of RSS," said Akshay Lakhra, NSUI leader.

The ABVP called it a "heinous act". "Last night, the humiliation done by the NSUI to the statue of Veer Savarkar at Delhi University is a heinous act and such an act for trivial political interests reflects the Congress' thinking of the great freedom fighter of India," said Monika Chaudhary, the national media convenor of ABVP.

The ABVP will make students aware about this "negative mindset" of the NSUI and its parent organisation, she said.  "In the context of this deplorable act, the ABVP urges the administration to take stern action against those involved in insulting the statue of freedom fighter," Chaudhary said.

Sources said DU Proctor Neeta Sehgal issued a show cause notice to former DUSU president Shakti Singh on Wednesday demanding an answer on his act of installing the bust without due permission from the authorities within 24 hours.

Shakti Singh's tenure as DUSU president ended on August 21. The Delhi University Students' Union polls will be held on September 12. On Wednesday, the ABVP had said it has instructed its office-bearers in the DUSU to shift the busts to the office till the time the university administration grants permission.