He said the Special Investigation Team (SIT) probing the killing had clues about the assailants, but those could not be disclosed at the moment.
"Who has done it...I am aware of it thanks to an update provided by the SIT. But I cannot disclose it now," Reddy said at a meet-the-press programme organised by the Press Club of Bangalore and the Bangalore Reporters' Guild here.
The minister, however, clarified, "Weeks do not mean one or two weeks. It (the arrest of the killers) will happen in a matter of a few weeks. This will happen 100 per cent."
Reddy said whether Lankesh was killed by left-wing or right-wing extremists or was it due to "some other thinking" was "one issue".
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Lankesh, known to be an anti-establishment voice with strident anti-right wing views, was shot dead at close range by unidentified assailants outside her residence here on the night of September 5.
Reddy had made similar claims about the SIT having gathered "some clues" in connection with the case earlier too.
The Congress government in Karnataka, which constituted the SIT headed by Inspector General of Police (Intelligence) B K Singh, has also announced a reward of Rs 10 lakh for anyone providing clues about the perpetrators of the crime.
As the killing gave way to a political slugfest, Lankesh's family had made a plea not to give a political colour to it.