Following a similar demonstration at the ministry in Moscow last month, the women -- some with young children -- positioned themselves with rucksacks and camping gear.

They said they were ready to spend the night there, in a video posted on a Telegram account of one of the protesters, who identified herself only as Paulina.

"At the moment the women are just located by the defence ministry without placards. They are asking for a meeting with the defence minister," Andrei Belousov, Paulina wrote.

"Basically we are waiting and waiting and waiting. We won't leave here without results," she added.

One of them was shown in a photo lying on a mat on the pavement outside holding her child.

The rare protest linked to Russia's military offensive in Ukraine followed another one on June 3, when women kneeled outside the building holding handwritten placards.

On that occasion, a ministry spokesman came out to address them -- an unusual move since Russian authorities almost never engage with protesters.

The women ended up leaving due to heavy rain.

Earlier in May, Russia branded a movement called "Put Domoy" (The Way Home) seeking to bring back men mobilised to fight in Ukraine a "foreign agent".

After that, women protesters told AFP they wished to remain anonymous and were not part of Put Domoy.

They continued to hold protests without inviting media, after journalists were arrested at demonstrations by Put Domoy.

A woman at the protest on Monday who gave her name as Lidiya told a policeman they had "no connection to the Put Domoy movement".

"We need the defence minister of Russia," Lidiya told the officer who came out to talk to them, saying she had come from Novosibirsk in Siberia.

"Our children and the husbands of these young women are in deadly danger," Lidiya said, after the policeman asked them to move to another place.

"My son was seriously injured. Now he has been sent again to the zone of the special operation without being fully healed," Lidiya said, adding that her son had been serving almost two years.

In a video posted later on Telegram, one of the women said they had met a representative of the ministry but "they did not tell us anything interesting.. Nothing interesting, nothing new. We are going back to the spot where we were standing."

Paulina wrote that well-wishers had brought the women and children food and water.