The government is planning “damaging cuts” to the Border Force, Labour says.
Shadow home secretary Andy Burnham quoted force members as saying they had been told to expect cuts of 6% in the next financial year and the one after.
In a letter to Home Secretary Theresa May, he said making savings now in the wake of the Brussels terrorist attacks would be a “very serious mistake”.
The Home Office told the BBC the Border Force’s budget for the next two years was still being finalised.
In the wake of the Brussels bombings, the government said it was deploying more Border Force staff to strengthen checks at UK entry points.
But Mr Burnham accused the home secretary of “going to great lengths” to conceal further cuts planned for the agency.
It was “highly unusual”, he said, for ministers to have not released the Border Force’s budget with the start of the new financial year only a few days away.
He said the force had “already experienced consecutive years of cuts” and was “stretched to the limit”.
“The public has a right to know about the government’s plans for the UK border and that is why I call on them to publish these figures without delay and to drop these damaging cuts,” he added.
The Home Office said extra money for the force had been promised in the chancellor’s Budget this month.
A spokesman said the government had “invested tens of millions of pounds to bolster security at ports in northern France” and would take “all the necessary measures” to maintain the security of the UK’s borders.
Labour is also calling for the UK’s sea border with Belgium to be strengthened, warning it could be a route for guns and explosives to be smuggled into Britain.
Mr Burnham says British border officials should be deployed to work alongside local staff in Belgian ports, as already happens in Calais.
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