According to local media, some of these protesters have called on Moscow to "rescue" them.

The subsequent arrests are seen as an attempt to stifle any fledgling support for Russia in Nigeria, a leading oil producer and a key ally of Western powers.

Several countries in the wider region of West Africa - including Nigeria's neighbour, Niger - have pivoted away from the West and towards Russia after recent military coups.

Civilian governments backed by the likes of France and the US had rapidly lost popularity - critics accused them of failing to tackle insecurity, corruption and economic problems.

Nigeria's President Bola Tinubu came to power in May 2023 after winning fiercely contested elections.

Satisfaction with his leadership has plummeted, with many blaming his policies for the sharp increase in the cost of living.

He scrapped a long-standing state subsidy on fuel in his inauguration speech, causing pump prices to rise. The move also had a knock-on effect on the cost of food and other basic commodities.

Mr Tinubu has urged frustrated Nigerians to be patient, insisting his policies would bear fruit.

He has appealed for an end to the protests and held a meeting with security chiefs on Monday to assess their scale.

Afterwards, army chief Christopher Musa said: "We are warning in clear terms that we will not accept anybody, any individual flying any foreign flag in Nigeria. That is a treasonable offence, and it will be viewed and treated as such."

The Russian embassy in Nigeria has distanced itself from the demonstrations, saying that the flags were the "personal choices" of protesters.

"As always, we emphasise that Russia does not interfere in the domestic affairs of foreign states, including Nigeria," it added.

On Monday, the north-western states of Kaduna and Zamfara saw a massive turnout of demonstrators.

Kaduna police spokesman Mansir Hassan said 39 people had been arrested there, including a tailor who was "sewing the foreign flags for the group".

Close to 40 Russian flags were confiscated, as well as a Chinese one, he added.

A curfew has now been imposed in Kaduna - the sixth state to take such action since last week, forcing millions of people to stay at home.

In a statement, Nigeria's secret service said tailors have also been arrested in Kano state for "making Russian flags".

"Some of their sponsors have also been picked. Investigation is ongoing," it said.

Rights group Amnesty International says 13 people have been killed since protests began last week and accused security forces of using excessive force against demonstrators.

Mr Tinubu addressed the nation on Sunday and said his government was committed to addressing the concerns of protesters.

He added that the protests had been hijacked by looters in some areas, and ending the unrest would create room for dialogue.