Palestinian authorities have arrested two union leaders on charges of membership of an illegal organisation, a non-governmental rights group said on Sunday.The Independent Commission for Human Rights said that Bassam Zakarneh and Moin Ansawi have been in Palestinian police detention since Thursday in the West Bank city of Ramallah.On Sunday the prosecution remanded them in custody for another 48 hours pending an investigation into allegations that they belong to "illegal organisations".Zakarneh heads the union of Palestinian government employees and Ansawi is his deputy.The Ramallah-based rights group expressed concern at their arrest and said it was closely monitoring the case, adding that two other union members had been arrested overnight Saturday.The union was set up in 2007 but in May a presidential committee declared it illegal.

Zakarneh's union has frequently called for strikes over labour disputes with the Palestinian Authority of president Mahmud Abbas and the rising cost of living.