They met in Romania before travelling across Europe by bus. Now, though, they are hunkered down in a hostel in the northern French port city of Calais after British border agents refused her sister permission to board the ferry without a visa.

"They asked for all these documents, and for them to be translated into English," Verbovetskyy, a hotel worker whose husband had travelled with her for support, told Reuters outside the hostel.

Verbovetskyy, exhausted by the journey and worried about her mother, who had stayed in Ukraine, said she wasn't sure the visa would come through because they did not have all the necessary paperwork.

Calais Mayor Natacha Bouchart estimated some 600 Ukrainians trying to reach Britain had been turned away at the port, half of whom were still waiting for a visa.

Bouchart made the local hostel available as emergency accommodation. Its 150 rooms are full and the local authorities say Britain needs to match its words with action.

"The British say 'we will welcome you' but then actually no, they close the door. It's inhumane," Bouchart said, standing outside Calais City Hall where both the French and Ukrainian flags were flying.

'WE WILL PRAY AND WAIT'

Unlike the European Union, which has said any Ukrainian fleeing the war can stay in the 27-member bloc for three years, Britain requires them to have a valid visa upon arrival.

Only those with family members in the Britain can apply for a visa. The British government has said a second visa route, requiring sponsorship from an organisation, charity or business, will soon be available.

"The routes we have put in place follow extensive engagement with Ukrainian partners," a spokesperson for Britain's Home Office said. "This is a rapidly moving and complex picture and as the situation develops we will continue to keep our support under constant review."

But Verbovetskyy said that even for those with family, the process is complicated. She went to Paris with her sister on Monday to apply for a visa at the British consulate and was told they would only have a response after six days.

"We will pray and wait," she said.

Paris and London have traded barbs over the British government's stringent approach.

France has urged Britain to set up consular services in Calais. Bouchart said Britain should simplify its procedures and suggested a "no visa" stamp for Ukrainians.

Calais is no stranger to Franco-British tensions over the management of migration flows. The port and surrounding coastline has long been a departure point for people trying to reach Britain via trucks and inflatable dinghies.

Hundreds of migrants from Africa and the Middle East, either fleeing war and persecution or seeking a better life abroad, are scattered in Calais.

Some charities allege a double standard in the treatment of migrants from Ukraine and those from elsewhere. Migrants in Calais have long complained of poor access to food, water and shelter.

"It is goodwill versus mistreatment," said Nikolai Posner, from the NGO Utopia 56 that assists migrants in Calais.

(Reporting by Layli Foroudi; editing by Richard Lough and Alex Richardson)

By Layli Foroudi