Muslim faithful listen to a sermons by an Imam before traditional Friday prayers at the Moddibo Adama Mosque in Yola, Nigeria, Feb. 24, 2023. [AP Photo]

Nigeria's state security service has warned the public of possible terrorist attacks on houses of worship ahead of the June 29 Islamic celebration of Eid-al-Adha, the Feast of Sacrifice. The Department of State Services says operations this week against armed men recovered improvised explosive devices, indicating plans to launch attacks before and during festivities.

The security advisory was contained in a statement released by Nigeria's secret police Thursday evening.

It's the first such warning by the Department of State Services, or DSS, since Nigerian President Bola Tinubu assumed office in May.

The DSS said the warning was based on the intelligence and recovery this week of improvised explosive devices found during counterterrorism operations in the central Kogi and Nasarawa states near the capital.

DSS officials said operatives killed a notorious gang leader and arrested a gun dealer during the raids Monday and early Thursday.

Secret police spokesperson Peter Afunanya did not respond to requests for further comments, but retired DSS officer Mike Ejiofor said the threat should be taken seriously.

"It's an advisory from the state security service for people to be on the watch out and, you know, such advisories are based on intelligence gathered or available to the service, so it's important that people are conscious of their environment," he said.

The security agency said it will work with the military and police to disrupt the terrorists' plans. Security issues have created major problems for past administrations.

Nigeria has been battling an insurgency that has lasted nearly 14 years, along with armed gangs who often kill or kidnap for ransom. Worship centers are often targets of terror attacks.

During his inauguration on May 29, Tinubu promised his government will prioritize restoring security. Monday the president fired all service chiefs and the head of the police and appointed new ones.

Ejiofor said it is a step in the right direction.

"To me it was a very welcome development," he said. "Security is paramount, there's need for them to also meet immediately and start strategizing on methods of handling the security challenges in the country."

In June 2022, heavily armed men invaded St. Francis Xavier Catholic Church in Owo, a town in southwest Nigeria, and killed 41 worshippers. Authorities blamed the attack on the Islamic State West Africa Province, or ISWAP.

A month later, ISWAP claimed responsibility for a massive jail break near Abuja that freed hundreds of inmates including terrorism suspects.

Security experts say threats of terror have increased since the incident.

Kabir Raji, national youth secretary of the Nasrul-Lahi-il Fathi Society of Nigeria, a Muslim prayer group, said the society is already undertaking additional security measures at various mosques.

"A meeting is going on on this now; the various zonal security secretaries have been engaged, security checks, inviting the police [and] the DSS to every worship center before the Eid, [and] during [the Eid], ensuring proper car parking, scanning machines and checks, we all have this in our various locations," Raji said.

For now, many citizens will be more vigilant as they attend celebrations.