A convicted Dutch rapist undergoing court proceedings in Malta has been re-arrested in Bulgaria, after another victim came forward saying he assaulted her in October.

Bulgarian media has reported that Johan Stellingwerf, 38, was arrested in Sofia and accused of raping a Hungarian woman in October in the Bulgarian capital.

Mr Stellingwerf, who has been dubbed the 'Valium rapist' because of the drugged drinks he gave his victims before abusing them, had been arrested over similar charges a few weeks before, on Boxing Day.

In that case, he had been accused of raping a 32-year-old woman in Sofia after meeting her at a bar and taking her to his home on Christmas Eve.

According to Bulgarian media reports, however, he was later placed under house arrest and prohibited from leading the country until the case is closed.    

Mr Stellingwerf was accused in 2013 of raping his ex-girlfriend in Malta and, while denying the charges, filed an application in court challenging the police to prosecute the woman for filing a false police report and lying under oath.

He was jailed in the Netherlands in 2007 on two counts of rape and three of attempted rape, after being deported from Brazil where he had gone into hiding. His sentence was reduced on appeal in 2010.

Mr Stellingwerf is also suspected of carrying out rapes in Spain and Poland.