French group Doctors Without Borders revealed on Wednesday that it had fired 19 staff last year for harassment or abuse. The Paris-based group, known by its French acronym MSF, said it had received 146 complaints or alerts last year, of which 40 were found to be allegations of harassment or sexual assault. It said in a statement that it had acted on 24 of these cases, firing 19 employees as a result. With 40,000 staff around the world, MSF is one of the worlds largest aid groups, best known for its work offering medical aid in conflict zones. "Even though reports of abuse have steadily increased, MSF is aware that abuse goes under-reported," the charity said, according to Agence France Presse. The revelations came as Oxfam grapples with allegations that it was not transparent about a scandal involving some of its staff for using prostitutes in Haiti following a devastating 2010 earthquake. The scandal has led to the resignation of Oxfams deputy head and has thrown into question British government funding for the charity, which amounted to around £32 million (36 million euros, $44 million) last year. Britain warned on Wednesday it would cut off ties with foreign aid charities that cover up sex scandals. "Unless you report every serious incident or allegation, no matter how damaging to your reputation -- we cannot be partners," Britains International Development Secretary Penny Mordaunt told a conference in Stockholm, according to extracts of her speech released by her ministry. Mordaunt called the Haiti prostitution allegations "horrifying". An Oxfam spokeswoman on Wednesday said the aid agency had received 1,270 cancellations of donations by direct debit between Saturday and Monday -- compared to a normal monthly average of 600.