The Hamas-led Government has defied a demand by Palestinian President Mahmoud Abbas to integrate its Gaza Strip military force into the established security set up. It then deepened the existing tension by announcing that it would double the size of the force to 12,000 men. The demand by Mr Abbas is likely to further increase the tensions between his Fatah movement and Hamas, which defeated Fatah in parliamentary elections a year ago. In a statement, Mr Abbas said he considered the Hamas force and its officers as ‘illegal’ and ‘outlawed’. This announcement came just two days after Hamas militants killed a senior Fatah security commander in Gaza. But a spokesman for Hamas says the force was created by the Hamas Government and can only be dismantled by another decision by the Hamas administration. Hamas created the force after forming the Government last March, and had defied a previous order by Mr Abbas to integrate the personnel into the existing security services. Meanwhile medics and witnesses in Gaza say three Palestinians have been killed and nine wounded in clashes between two powerful clans.