The Yung Rapunzel star kicked off the spat earlier this month (07Jul13) with a cryptic tweet that read: "weak... she can't talk though. Not when I met her coked up at yoyo... And Not with that ugly husband she has."
Allen responded on Thursday (11Jul13) with, "better not be, meh (sic)," prompting Banks to confirm she was attacking the Smile singer, adding, "@lilyrosecooper your husband looks like a thumb."
That angered the tough-talking singer, who fired back with, "Not even gonna @ her but if she wants to talk about weak, I'm sure her record sales to date should suffice. One hit wonder... And my husband? Don't go there b**ch Or your totally unnecessary security detail may actually have something to worry about."
The bickering continued when Banks tweeted, "@lilyrosecooper Lol ill be a one hit wonder but you have ugly children and a coke habit... Shhhhhhh."
It is not clear what first sparked the ugly war of words.
Banks' tweets landed her in the headlines earlier this year (13) after she upset gay rights groups by using a homophobic slur in a furious online rant aimed at celebrity blogger Perez Hilton.
The 212 hitmaker became embroiled in a feud with openly-gay Hilton back in January (13) after he labelled her "pathetic", prompting Banks to hit back and brand the gossip blogger a "f**got", adding that he should "just kill" himself.
The hip-hop star initially defended her angry words, insisting, "A f**got is not a homosexual male. A f**got is any male who acts like a female. There's a Big difference", but she subsequently backed down and apologised to her fans.
She tweeted, "My most sincere apologies to anyone who was indirectly offended by my foul language. Not sorry for Perez tho (though)."
However, Banks' apology was not enough for officials at the Gay and Lesbian Alliance Against Defamation (Glaad), who condemned the star's use of the derogatory term.
A statement issued by Glaad representatives read: "Banks' claim that the word 'f**got' doesn't mean a gay male is not true. Regardless of her intent or her personal definition, what matters is the meaning given to that word by those who hear it, and the damage it causes when they do."