Mumbai, Feb 22 (IANS): Around 20 Aam Aadmi Party activists, including its leader Mayank Gandhi, were detained Saturday while on their way to a "sweep clean" agitation against the Nationalist Congress Party for an attack at the AAP state office by NCP activists earlier in the day.

"Gandhi and around 20 others were going to the NCP office in Telli Gully, Andheri east, with brooms but police detained them en route," an AAP spokesperson said.

The AAP said its agitation was in retaliation against the NCP, whose activists attacked the AAP state office, also located in Andheri east earlier Saturday.

"Around 25-30 NCP activists swooped down on our party headquarters, shouting slogans against us. They grabbed a bundle of our banners and publicity material and made a bonfire of it," AAP city treasurer Suresh Acharya told IANS.

The AAP will continue the agitation against the NCP after police allowed its leaders to go, the spokesperson said.

The incidents took place in the Mumbai northwest Lok Sabha constituency from where Gandhi will be the AAP candidate.

"Over 100 party activists have decided not to go home till we go to the NCP office and offer prayers asking the almighty to grant them good sense and not indulge in violent activities," the spokesperson added.

Acharya said the NCP activists also smeared the AAP office hoardings with blank ink, tore down posters of party chief Arvind Kejriwal and left after a noisy demonstration.

There were, however, no casualties in the incident, he said.

Acharya said the immediate provocation for the attack could be the AAP's ongoing campaign against NCP leader and Deputy Chief Minister Ajit Pawar on alleged corrupt practices in the power department handled by Pawar.