Nigeria has detained some tailors for making Russian flags that were waved during anti-government protests this week in northern states, the state secret police said, in a move that underscores concerns about increased Russian activity in western Africa.

The Department of State Services (DSS) also said in a post on X that it had detained some of the tailors' "sponsors", without elaborating. It said an investigation was ongoing. It did not say how many tailors or "sponsors" had been detained.

Nigeria's Chief of Defence Staff, General Christopher Musa, described the brandishing of a foreign flag during anti-government protests as a "treasonable offence" after he held security talks with President Bola Tinubu on Monday.

"We have identified those (sponsoring them) and we are going to take serious action against that," Musa told reporters, also without elaborating.

Hundreds of thousands of Nigerians have been protesting since August 1 against Tinubu's painful economic reforms that have seen a partial end to petrol and electricity subsidies, currency devaluation and inflation touching three-decade highs.

The protests have now ebbed after a deadly police crackdown.

In the northern states of Borno, Kaduna, Kano and Katsina, protesters were seen waving hundreds of Russian flags with some calling for a military takeover.

"We are waving the Russian flag because Tinubu's government is not listening to us. Russian presidents always support African nations' development, unlike other nations," Lawal Kodo, a 28-year old protester in Kano, told Reuters on Monday.

RUSSIA 'NOT INVOLVED'

The Russian embassy in Nigeria denied any involvement.

"The Government of the Russian Federation as well as any Russian officials are not involved in these activities and do not coordinate them in any way," the embassy said in a statement issued late on Monday.

The protests in Nigeria, Africa's most populous country, come amid increased Western concerns over Russian security ties with the region, including countries such as Mali, Burkina Faso and Niger where military leaders have seized power in coups.

Security experts said many Nigerian protesters believe that the cost of living crisis is the result of reforms dictated to Tinubu by Western institutions such as the International Monetary Fund and the World Bank.

"The Russian flags that appeared during the protests in northern states, and the calls for a military coup, reflect discontent over the government's policies rather than showcasing support for a Russia-backed military government," said Mucahid Durmaz, Senior Analyst at Verisk Maplecroft, a global risk intelligence firm.