Profits at some of the UK’s best-known charity shops have plummeted as they face a number of pressures, including from online secondhand clothes platforms, prompting claims that a key part of the sector’s fundraising model could be under threat.

According to unpublished accounts seen by the Financial Times, Oxfam’s retail profit fell 23% to £4.9m in the last financial year, compared with £6.4m in the previous year.