Invoking Shiv Sena founder and his uncle late Bal Thackeray, the Maharashtra Navnirman Sena chief said he had left the Sena in 2006 because of similar "dirty politics".
The BJP, the second largest party in the Sena-controlled Brihanmumbai Municipal Corporation (BMC), had also accused the Sena of indulging in "horse trading" in the wake of the defection.
However, Mr Uddhav Thackeray had termed the entry of MNS corporators to his party as "ghar wapsi", given that they were part of the Sena before breaking away with Raj Thackeray in 2006 when he had floated the MNS.
"Each MNS corporator has received Rs 5 crore from the Shiv Sena. It is a very low level of politics and I will never forget it," Mr Raj Thackeray told reporters.
After Friday's development, the MNS, which once projected itself as a strong alternative to the Sena by playing the aggressive politics on the "son-of-soil" issue, has now been left with just a single corporator in the BMC. The MNS had 27 corporators after the 2012 elections. The number dwindled to seven in the BMC polls held earlier this year.
The Raj Thackeray-led party is now struggling to secure its registration as a political party and the space given by the BMC administration to the party in its headquarters in south Mumbai.
"Late Balasaheb Thackeray never indulged in such dirty politics of money, when he was heading Shiv Sena. I left Sena only because of such dirty politics. I will never forget such low level of politics, where you take interest in splitting a party," Mr Raj Thackeray said.
Trying to put up a brave force, the MNS chief said the corporators could have left the party with pride instead of "accepting money".
The six corporators joined the Sena a day after the BJP won a civic bypoll in Mumbai by defeating the Sena candidate in suburban Bhandup.
The move to wean away the MNS corporators is viewed as a masterstroke by Mr Uddhav Thackeray, as it helped his party raise its tally in the 227-member house to 90, eight more than the BJP.
Political observers say with this move, Mr Uddhav Thackeray denied any chance to the BJP to either match the Sena's tally in BMC or even surpass it.
In the BMC polls held earlier this year, the Sena had won 84 seats, and the BJP 82.
The Sena also enjoys the support of four Independent corporators, while the BJP has the support of two Independents.
The Bhandup by-poll victory would have taken the BJP's tally in the BMC to 83, however, it remained 82 due to the death of a BJP corporator from western suburbs last month.
After the Bhandup win, senior BJP leader Kirit Somaiya had said the BJP would install its Mayor in Mumbai, rankling the Sena.
The Sena and the BJP, though allies in the central and Maharashtra governments, do not have a formal tie-up in the Mumbai civic body.