The army is expected to begin training on 21 November to replace striking Border Force officers at ports and airports, Home Office staff have been told. The Guardian understands that more than 500 military personnel are expected to each receive five days of training before being asked to work in frontline jobs. The first are supposed to arrive for training a week on Monday, Home Office staff have been told. Managers sent memos to staff on Friday suspending the launch of basic training for other new Border Force guards, which usually takes three weeks, in anticipation of the arrival of members of the armed forces. But in a sign of tension between government departments, the Ministry of Defence said it had not yet agreed to the secondment of its staff to the Home Office, despite receiving a written request. The developments follow a vote on Thursday in favour of industrial action by the Public and Commercial Services union, which represents Border Force guards across the UK. The Guardian disclosed on Thursday that plans signed off by the home secretary, Suella Braverman, said military personnel would be given training of less than a week so they could cover jobs at ports such as Dover and airports including Heathrow. They could also be expected to process people coming across the Channel in small boats, amid an expected increase over the next few weeks. Formally the Home Office has to ask for help under the military aid to the civil authorities protocol and in the past few days submitted its demand for several hundred soldiers to plug the anticipated staffing gaps at ports and airports. That has prompted a debate within the MoD as to whether the request should be met in full or in part, although there is a recognition that the Home Office has few options. No final decision to deploy military personnel had been made as of Friday afternoon. The request will have to be signed off by the minister – likely to be the defence secretary, Ben Wallace, given the sensitivity of the deployment – and in some previous cases the MoD has rejected requests for help, arguing there was a simpler way for a domestic department to solve the problem. It is also understood that senior Border Force staff have been asked to seek training so they can also check passports in the event of a strike. Reacting to the developments, the PCS general secretary, Mark Serwotka, said: “This is pure desperation by Suella Braverman. Time and again, the military has been clear it has its own job to do and doesn’t want to spend time covering for the government’s failures. “The government’s attempts to recruit a strike-breaking workforce from within the civil service has also clearly failed, which is no surprise when it continues to treat its workforce with contempt, offering them only a 2% pay rise. “Instead of scrambling around for increasingly desperate solutions, the government should sit down with us at the negotiating table and agree a fair pay rise.” The former armed forces minister John Spellar said he had met resistance when he tried to call in the military to tackle fuel protests under Tony Blair. “They do not like getting involved in industrial disputes, and so I cannot imagine that they will like this idea,” he said. The Border Force has come under increased pressure from the rise in small boat crossings in the Channel. The Home Office is also being pressed to reduce the overcrowding at Manston and other processing centres for asylum seekers. A Home Office spokesperson said: “We are disappointed that the union has voted in favour of industrial action. Our priority will always be to keep our citizens safe and borders secure, and we will not compromise on this. “As the public would expect, we have plans in place to minimise potential disruption during possible strike action, while still carrying out essential checks.”