The total cost of the Government's pledge to resettle 20,000 Syrian refugees could top £1.7 billion, spending watchdogs estimate.

The National Audit Office (NAO) warned that a shortage of housing and school places could pose a threat to the chances of meeting the pledge by 2020.

However, the sum is uncertain in some parts as it depends on the characteristics of those entering the country, the extent to which refugees need medical treatment or welfare services, and the extent to which they can gain employment and become self-sufficient, according to the NAO.

It is estimated that each refugee will cost £17,340 each year, for their first five years in the UK, with money spent on healthcare, education and welfare.

As of June 2,659 refugees had been resettled in the UK through the programme - 13% of the target, with those arriving dispersed across 118 local authorities.