Britain’s foreign secretary David Lammy is pushing for an emergency top-up to development spending as ballooning costs of supporting asylum seekers threaten to drain overseas aid to its lowest level since 2007.

The UK government spent ￡4.3bn hosting asylum seekers and refugees in Britain in the last financial year, more than a quarter of its ￡15.4bn overseas aid budget, according to official data. This more than consumed the ￡2.5bn increases in the aid budget scheduled between 2022 and 2024 by former Conservative chancellor Jeremy Hunt.

People familiar with Lammy’s thinking say he fears that if Rachel Reeves, the chancellor, resists calls to at least match Hunt’s offer, the aid budget will be further eviscerated, undermining the government’s ambitions on the global stage.