Verbal duel between the two sides were witnessed in both Lok Sabha and Rajya Sabha during special discussions on the issue for which Left and BJP had given notices.

Left parties and Congress targetted the BJP accusing it of attacking CPI(M) headquarters on Sunday while the saffron party alleged that the Communist activists started violence when its workers went there to stage a "peaceful" protest against killing of its cadres in Kerala.

In Lok Sabha, CPI(M) was joined by Congress in its attack on the BJP and the ensuing clash between the two sides led to pandemonium in the House.

After about 25 minutes of verbal duel, BJP members rushed into the well of the House, provoking Speaker Somnath Chatterjee to reprimand them for the action.

"It is a matter of great sadness and sorrow... One of the major parties, after speaking itself, is not allowing others to speak. I condemn it," Chatterjee said and adjourned the House for 50 minutes.

Earlier, initiating the discussion for which notices had been given by both Left parties and BJP, CPI(M)'s Mohd Saleem said activists, who were clearly from BJP, attacked the CPI(M) headquarter and tried to enter inside.

Saleem said those indulging in the act were so "ashamed" themselves that they did not display any flag.

Four BJP Corporators of Delhi were involved and a party flag was found in a car in which stones were brought for pelting at the CPI(M) headquarter, Saleem alleged amid protests by opposition.

He claimed that RSS as also Leader of Opposition in Delhi Assembly Jagdish Mukhi (of BJP) had taken responsibility for the violence, evoking protests from BJP members.

"RSS was itself so ashamed that it used the name of some Hindu Manch. Why are they using Hindu name to indulge in violence? I condemn it," the CPI(M) member said.

He, however, said he did not believe that the attack by BJP would have been planned by the saffron party's central leadership.

BJP's Deputy Leader in the House V K Malhotra said the protest staged at the CPI(M) headquarter against what happened in Kerala was intended to be "peaceful" but the Communist cadres from inside pelted stones on the demonstrators, injuring 15 of them.

"It was pre-planned by CPI(M)," he alleged and said BJP had filed FIR citing how the CPI(M) cadres were "incited" by their leaders.