The deputy chief of Indonesia's anti-graft agency will submit his resignation letter on Monday, days after the police named him a suspect in a false testimony case, an agency official said.

Police on Friday detained and questioned Bambang Widjojanto, deputy chief of the Corruption Eradication Commission (KPK), for a case dating from 2010, fuelling tension between two law enforcement bodies that have long had strained relations.

"Bambang will submit his resignation letter today," Johan Budi, KPK's deputy for corruption prevention, told Reuters.

Widjojanto, who told domestic media on Saturday he was considering resigning, was not immediately available for comment.

The head of the KPK, Abraham Samad, told domestic news website Detik.com on Saturday that he would not accept a resignation letter from Widjojanto, who is one of four KPK commissioners.

KPK supporters believe Widjojanto was named a police suspect in retaliation for the agency's decision to declare police general Budi Gunawan a bribery suspect on Jan. 13. That announcement led President Joko Widodo to delay Gunawan's appointment as the next police chief.

The police said its actions against Widjojanto were not linked to the agency.

The apparent tit-for-tat actions reignite a rivalry between the graft-tainted police and the independent agency, popular among ordinary Indonesians for being a thorn in the side of the establishment.

Resolving the situation will prove an early test for Widodo, who took office in October, pledging a clean government.