Labour leader Keir Starmer said it was "fantastic" to welcome Poulter to the party
The police linked them to violence at Jagannathpur in Hazratpur union and Manu Beparir Dhal in Jinjira union on Wednesday.
SI Md Farhad Hossain in Keraniganj Model Police Station and SI Anwar Hossain in Kalatia Police Post filed the cases, according to Keraniganj Model Police Station Chief Saker Mohammed Zubair.
SI Anwar Hossain in Kalatia Police Post charged 209 persons in a case that also mentions 150 unidentified BNP leaders and activists.
On the other hand, SI Md Farhad Hossain in Keraniganj Model Police Station filed a case against 49 BNP leaders and activists along with 100 others unnamed.
No-one has been arrested over the cases as of Wednesday, said police.