British nationals living in Berlin have been reassured that an urgent registration process to secure legal status will be in place for them in the event of the UK leaving the EU with no deal.

Worried Britons who attended a meeting hosted by the British embassy said they felt relief that the state authorities had been able to go further than the European commission, whose no-deal planning announced this week made them feel abandoned.

There are an estimated 100,000 Britons living in Germany, the majority of them working, but they fear they will be treated as third-country nationals after Brexit, last in the queue for jobs after Germans and EU nationals, as is the legal norm for people from outside the bloc who apply for work.

Berlin recently overtook North Rhine-Westphalia as the state with the most UK nationals with 18,000, the ambassador said in his opening remarks.

Engelhard Mazanke, the head of the foreigners registration office at the Berlin state office for citizens, told Britons that he could not say what kind of residence status they would get when the UK leaves the EU, or what documents would be required.

He promised, however, that the immigration office would clarify the situation as soon as possible and be “very generous” with UK nationals in Berlin who have to go through the federal legislative process to establish their new status.

He told them it would take eight weeks for the immigration office in Berlin to issue residence permits and that it would not be possible before 29 March, but he reassured Britons in the audience that the city had an “excellent, flexible team which coped with the refugee crisis two years ago”.

He told them that Britons would be able to register their personal details on an official website by the second week of January, to help establish that they have a continued right to live and work in the state in the event of no deal.

One British national at the meeting said they felt that at last someone had listened to them after two years of anxiety. “His statement is remarkable, in my view because he, as the first of the heads of the immigration offices in Germany, is willing to come out at this stage and put Brits’ minds at rest,” the source said.

France also sought to reassure British nationals of their post-Brexit status.

The Europe minister, Nathalie Loiseau, said the country would guarantee the residence, employment and welfare rights of the 160,000 British citizens living there provided that Britain offered the same guarantees to French expatriates.

The campaign group British in Europe, which is chaired by the Berlin-based lawyer Jane Golding, wrote on its website on Saturday that “a ministerial decree would be adopted and British citizens would have a three-month transition period post March 2019, during which they would be exempt from needing whichever new status would ultimately apply to UK citizens in Germany”.

Golding said that UK nationals would still be losing some of their rights and called on Brussels and London to do more to ensure those affected retained those rights whatever the deal.

“There are some unanswered questions and we will be following up with the relevant authorities in the new year. We also know that there is still some EU-wide coordination going on behind the scenes. But it shouldn’t be left up to the EU27 to give us reassurances, which is where a no-deal leaves us.

“The responsibility falls squarely on the UK government to do all it can to make sure its citizens, wherever they live, are protected,” she said.

Brussels has urged European governments to take a generous approach to protecting the rights of 1 million Britons living in the EU if the UK leaves without a deal.