Anastasia Lenna, who represented her country in the 2015 Miss Grand International beauty contest, has signed up to defend her home from Russian forces.

"Everyone who crosses the Ukrainian border with the intent to invade will be killed!" a message posted on her Instagram on Saturday said.

It was accompanied by a photo of armed soldiers blocking a road.

Follow live updates: Ukraine says '4,300 Russian troops have been killed or injured'

'NATO should apply for entry into Ukraine'

Another post said: "Our (Ukraine's) army is fighting in such a way that NATO should apply for entry into Ukraine."

She also posted a photo showing soldiers walking with Ukrainian President Volodymyr Zelenskyy, who she called "a true and strong leader".

Key developments:

• Putin orders military command to put nuclear deterrent forces on high alert
• Ukraine and Russia set to hold negotiations on Belarusian-Ukrainian border
• Zelenskyy says Saturday night was 'brutal' with Russian forces 'attacking civilian areas'
• Seven-year-old girl reported among dead in shelling in Sumy, northeastern Ukraine

Call to remove road signs

In one post, Ms Lenna calls on Ukrainians to remove all road signs to make it difficult for invading soldiers to navigate through Ukraine, according to The Sun.

"Dismantling road signs on all roads of the country. The enemy has a pathetic connection, they don't orientate the terrain. Let's help them go straight to hell," she wrote.

"The State Road Agency of Ukraine calls on all road organisations, territorial communities, local authorities to immediately start dismantling road signs nearby."

Ms Lenna, a marketing and management graduate from Slavistik University in Kyiv, previously worked as a model and public relations manager in Turkey. She has also worked as a translator and speaks five languages.