An unprecedented crisis has gripped Youth With A Mission (YWAM) in England and Wales, with a Home Office clampdown forcing it to face sending more than 350 international staff home.

Following an inspection in September by UK Visas and Immigration (UKVI) officers reviewing the charity's status as a visa sponsor, YWAM was notified in December that its licence would be suspended for 20 working days and would be revoked if outstanding issues were not addressed.

If the visa sponsorship licence is revoked up to 350 missionaries and their families – about half YWAM's current workforce – will have 60 days in which to leave the UK. The figure represents about half the current workforce, all of whom are volunteers who have raised their own funds to work with the organisation.

According to the charity, this would "inevitably mean shutting down some of our training and service opportunities in this nation and abroad".

YWAM says that in the September report they were found to be compliant in five of the seven areas audited and that there were "some clerical issues" in the other two which they immediately formed a team to rectify. However, it was informed of other issues on December 23 and told that its licence was being suspended. YWAM said: "Whilst we recognise and support the UKVI's legitimate right to concern over compliance to the rules, we do not feel that the issues raised in the letter from the UKVI justify such a draconian outcome as losing our licence would produce.

"We are cautiously hopeful that through dialogue and by demonstrating our determination to follow the regulations as carefully as possible they will allow us to continue our operations in the UK as part of a global charitable faith-based movement."

The strict visa and immigration rules are aimed at clamping down on colleges and other organisations used as fronts for illegal migration. Spokesman Mark Venning told Christian Today that YWAM supported the principle of the regulations, but that faith-based organisations were suffering unintended consequences. The last inspection, he said, represented a marked shift in tone from relations with UKVI during the previous six years. However, he added: "We are in the process of responding in as good a heart as we can."

Venning said that the consequences of losing sponsorship status would be "profound", as many mission workers came from abroad for training and service. As well as their contribution to YWAM's ministry, they also represent the only form of external revenue for the organisation, whose workers are all self-funding. "It would severely affect us," he said. "In Wales, where I work, we have 14 workers, 10 of whom are here on visas."

Among other activities, YWAM supports churches in running foodbanks, Street Pastor programmes, ministry to homeless people and youth clubs.

YWAM has called for a day of prayer tomorrow, saying: "As we know, we fight not against flesh and blood, but against those dark powers the Bible describes as 'spiritual forces of evil in the heavenly realms' (Eph 6:12 ESV). As such we have made it clear that our only prayer for the UKVI and those who serve within it is to be one of blessing. We reserve any battling prayer engagement to resist the enemy alone."

It is also encouraging supporters to write to their local MPs expressing their concern.

A Home Office spokesperson told Christian Today: "We continually and routinely monitor all licensed sponsors. Where we find evidence that sponsors are not fulfilling their duties we will suspend or remove their licence." She said that it would be inappropriate to comment further at this stage.