Priti Patel has been accused of presiding over chaos after Ukrainian refugees arriving in Calais were greeted by posters telling them to get their UK visas in Paris or Brussels, while her pledge to expand the visa scheme was contradicted by Downing Street.

On a day of confusion and uncertainty for Ukrainian refugees making the 1,400-mile journey to Britain, the home secretary admitted that she has not yet set up a visa application centre (VAC) near the French port of Calais, where refugees have gathered. It also emerged that the UK office in Brussels is open for only three half-days a week to process applications.

The details emerged at the end of a difficult day for Patel, who had earlier claimed she would introduce a new humanitarian route to enter Britain only to be contradicted by Boris Johnson.

The prime minister is under pressure to welcome more refugees from Ukraine following the heavy bombardment of civilians by the Russian army. Of the 1.3 million-plus Ukrainians to have fled since Russia invaded, the UK has said it will only take those with family connections or sponsorship by a third party.

Appearing before MPs on Monday, Patel said her department was in the process of setting up a VAC “en route” to Calais to cross the Channel to Britain. “We have staff in Calais, we have support on the ground. It is wrong to say we’re just turning people back, we’re absolutely not, we’re supporting those that have been coming to Calais,” she said.

Stella Creasy, the Labour MP, said: “As of an hour ago there was a poster in Calais saying, ‘No visas delivered in Calais.’ It tells people to go to an online form and then go to Paris or Brussels.”

Yvette Cooper, the shadow home secretary, questioned why there were so many reports of Ukrainians in the French town unable to apply for a visa because there was no official available to process applications.

“I hope the home secretary is going to deliver some of the promises she has made, but there is a huge gap between the rhetoric and the reality that is badly, badly letting Ukrainian families down,” Cooper said.

The Commons clash came after sources close to Patel confirmed reports that she was pushing through proposals for a third Ukrainian visa scheme. The Sun had quoted Patel as saying she was “investigating the legal options to create a humanitarian route”.

On Monday morning, a Home Office source told the Guardian a third route was being considered, in line with the Sun’s claims.

“As the crisis is developing it is becoming clear some people have needs that go beyond what sponsorship can offer and she does not want to see anyone excluded – hence why [a separate humanitarian route is] being considered with partner governments,” the source said.

However, the prime minister’s spokesperson contradicted this soon afterwards, saying Patel had been referring to a route announced last week, which allows Ukrainian refugees to be sponsored to come to the UK by a third party. “We have set out the two routes we are putting in place. The sponsorship route is a humanitarian route,” the spokesperson said.

In a televised clip, Johnson said any humanitarian route would still check each individual applicant before they were allowed into Britain. “Let me be very clear, what we won’t do is have a system where people can come into the UK without any checks or any controls at all,” he said.

James Cleverly, the minister for Europe and America, had also earlier contradicted Patel, telling the BBC there were no plans for a specific humanitarian route for Ukrainians.

“No, this is what has been in place previously,” he said. “We need to have some sort of process. We need to know who is here, where they are staying, what support they might need, if there are child protection issues. Whilst all of us would want to throw our arms open and be as generous as possible, there does need to be a process.”

Ministers are facing pressure to do more, including from some Tory backbenchers. Asked if the UK refugee scheme had been a failure, Tom Tugendhat, who chairs the foreign affair select committee, told LBC Radio: “It’s certainly not a success, is it? What we need to do is to make sure that … the Home Office is absolutely delivering to make sure we get support for those who are most in need.

“The British people are extremely generous … This isn’t some sort of illegal scam. This is perfectly obviously people fleeing for their lives and we need to be absolutely there to support them.”