Guwahati, Dec 29 (IANS): Nine BJP members, including two senior leaders, have been arrested for their involvement in an attack at the Congress state headquarters here, as Chief Minister Tarun Gogoi on Tuesday ordered a probe into Monday's clash between Congress and BJP workers that left many people injured.

Gogoi said an additional chief secretary level officer will carry out the probe and submit a report to him by 15 days.

Gogoi termed as "pre-planned" the attack by BJP workers at the Congress headquarters 'Rajiv Bhavan'.

He accused the BJP of trying to bring in "gundaraj" (hooliganism) to Assam ahead of next year's assembly elections.

"We have already ordered a probe and there will be action against the guilty," Gogoi said.

"The attack on Congress workers inside Rajiv Bhavan is not only condemnable but also a rare in the whole of India. They (BJP) are trying to bring in 'gundaraj' to Assam. The incident indicates that they are trying to scare Congress workers ahead of next year's polls," Gogoi said.

He said this indicated that the BJP will use "muscle power" in the polls.

"They resorted to gundaraj when there is a Congress government in Assam. One can well imagine what will happen if they come to power in Assam," he said.

Without naming his former minister and now BJP leader Himanta Biswa Sarma, Gogoi said there were reports that he may be involved.

"Two BJP leaders who were involved also have criminal records against them. I do not want to name them at present but the whole truth will come to the fore after completion of the probe," Gogoi added.

The BJP workers were agitating on Monday over an objectionable remark by former agriculture minister Nilamoni Sen Deka on union Human Resource Minister Smriti Irani.

BJP leaders, on the other hand, claimed they were demonstrating peacefully outside Rajiv Bhavan, when some Congress workers pelted stones and hit them with bamboo sticks.