Ukrainian protesters in London said they are “heartbroken” and “terrified” as they called on the UK to do more to stop Vladimir Putin taking over their country.

Hundreds of demonstrators gathered outside Downing Street on Thursday afternoon to call for more drastic action from Britain and the international community, including “total isolation of Russia” as its troops invade Ukraine.

The crowd sang the Ukrainian national anthem and chanted: “Stop Putin. Stop the war”, and “Ukraine is not Russia”.

People also held up placards with images of Mr Putin saying “terrorist”, “killer”, and “Putin! Get out of Ukraine”.

Natalia Ravlyuk, a volunteer who helped organise the protest, told the PA news agency: “We want the toughest sanctions and total isolation of Russia now.”

She said: “We feel very angry, we feel very anxious and we feel betrayed by democratic states because we have been talking about this war for eight years.

“They just need to wake up and stop Putin now.”

Olga Gevorkyan, 30, who has been in the UK for around a year, told the PA news agency that her entire family and all her friends are still at home in the northern Ukraine near to the Belarusian border.

Growing tearful, she said: “I am crying since this morning.

“I’m afraid to lose contact with them because it could happen any day.

“I have everyone – my family, my close friends, my heart and soul is there.”

Olesya Khromeychuk, 38, director of the Ukrainian Institute in London, whose brother died fighting on the frontline in the Donbas region in Ukraine in 2017, said she feels “awful”.

“The international community has to stand with Ukraine,” she added before calling on Britons to “stay informed from reliable sources”, “take to the streets”, “write to your MP”, and “stand in solidarity”.

Dmytro, 32, another Ukrainian national who did not want to give his last name, said: “When someone just invades your home, it is devastating.

“It feels like someone has just ripped through part of you.”

He also said the current sanctions were “not enough” and that they will hit the lives of ordinary Russians but “have little effect” on those with money and power.

Eugenia Klochko, 37, who has been in the UK for 10 years, also grew emotional as she spoke about her family who are still in Ukraine, saying: “I have had a couple of weeks of sleepless nights, monitoring the news, checking up on my family.

“I’m devastated. I’m heartbroken.

“I’m not sure if I’m going to see them alive again.

“I feel numb, terrified and shaken inside.

“I have never experienced or felt anything similar.

“If I didn’t have a child, I would probably be on the front line fighting for my country.”

Kenneth Nowakowski, the Ukrainian Catholic Church’s bishop for the UK, called on Britons to “stand in solidarity” with those in the country.

“Today we woke up to a day that we prayed we would never see.

“My first action was to pray for our brothers and sister in Ukraine and pray for those working towards peace.”

Meanwhile, Liberal Democrat leader Sir Ed Davey, who stopped by the protest, told the crowds: “I hope that we can get our Prime Minister today to be as strong as we need him to be.

“We need Britain to lead, leading Nato, leading the world.

“The people of Ukraine deserve that.

“The peace of our world needs that.”

Earlier on Thursday dozens of protesters also gathered outside the Russian embassy in Kensington waving flags and holding placards, including ones reading: “Stop Putin – stop war” and “Ukraine will never surrender”.