The PDP faction says the former secretary is a contractor to government who was blackmailed to abandon his camp.
The "New" Peoples Democratic Party, PDP, has appointed Abubakar Gambo Umar to replace Tamko Gwamna who resigned on Sunday.
A statement by the National Publicity Secretary of the splinter group, Chukwuemeka Eze on Monday, also said that Mr Gwamna did not resign but was sacked.
The former treasurer announced his resignation via a statement on Sunday barely a week after his appointment. He also pledged loyalty to the National Chairman of the PDP, Bamanga Tukur.
The splinter group accused Mr Gwamna of being a mole hence he was relieved of his position. It said that the report on the true status of the former treasurer was tabled during the inaugural meeting of the National Working Committee, NWC, of the "New" PDP on September 15.
The statement said that the National Secretary of the group, Olagunsoye Oyinlola, submitted the "damning report' on Mr Gwamna exposing him as a mole who could sabotage its activities.
Mr Eze had told Premium Times via a text message on Sunday night that the Presidency forced Mr Gwamna to resign because of a contract he was promised.
"We have read with dismay the purported resignation of our erstwhile National Treasurer, Alhaji Tanko Isiaku Gwamna, while the fact is that he was sacked by the party," the statement said in the statement on Monday.
"This unprincipled politician was sacked after being discovered to be a mole and has since been replaced by a seasoned and principled politician, Engr. Abubakar Gambo Umar, who has been an active grassroots politician and mobiliser in his native Taraba State since 1999.
"Alhaji Gwamna's fate became sealed when a report on his true status was tabled before the National Working Committee of PDP during its inaugural meeting held at the residence of the party's National Chairman, Alhaji Abubakar Kawu Baraje, in Abuja on 15th Sept, 2013.
"The damning report on Alhaji Gwamna was submitted by the PDP National Secretary, His Excellency, Prince Olagunsoye Oyinlola.
"According to the report, it was found that Alhaji Gwamna was a mole planted by the Tukur faction of PDP to monitor our activities and report back to it with a view to sabotaging our activities.
"Prince Oyinlola's report further indicted Alhaji Gwamna as one of those executing contracts for the Federal Government and under threat to have all his contracts terminated should he fail to spy on us as directed.
"Like the Judas that he is, Alhaji Gwamna agreed to mortgage his conscience in his mistaken belief that he could successfully sabotage our mission to bring sanity to our party being hijacked by hawks whose aim is to destroy a party that they do not know how it was formed."
The New PDP said Mr Gwamna hurriedly resigned when he got wind of his impending sack, adding that he rushed to the Presidency to alert it of his fate.
The statement said, "When Alhaji Gwamna got wind of his impending sack, this false democrat rushed to the Presidency to alert his paymasters that he had been discovered to be a mole and was at the verge of dismissal.
"To save his ugly face, the Presidency quickly drafted a press statement announcing his resignation and gave him to sign and immediately release to the press last night.
"To us, Alhaji Gwamma is rubbish meant for the dustbin and we sincerely thank all those who assisted us to discover on time this undemocratic personality only meant for a fading group like Tukur's faction of the PDP."
The group said Mr Umar was better qualified for the position of treasurer just as it apologised for not properly investigating before he was appointed.
"We are happy to announce the better qualified and more principled Engr. Abubakar Gambo Umar as his replacement with immediate effect. Unlike Alhaji Gwamma, Engr. Umar, who was twice nominated by his constituency to run for the House of Representatives, is a staunch believer in the rule of law, a democrat to the core and a man known for upholding justice and fair play.
"To Nigerians, we apologise for not properly investigating Alhaji Gwamma, a fellow who is ready to sell his conscience for a mess of porridge, before giving him such an exalted position of National Treasurer of a great party like PDP.
"As we bid him goodbye to his journey to political perdition and wilderness, we wish to urge all Nigerians to keep faith with us as we are very determined to flush out all the undemocratic elements that have constituted themselves a nuisance to our rescue mission."