Tension is rising on the streets of Gaza where security forces from rival Palestinian factions have been making their presence felt. Armed men from a new 3,000-strong force allied to the Hamas government which took power after winning a general election in January held ground on many streets.Outside his office, Palestinian Prime Minister Ismail Haniyeh told the men that their security unit – deployed for the first time on Wednesday – was legitimate and would not be disbanded. That sent a clear message to Palestinian President Mahmoud Abbas, as members of one of several forces loyal to his Fatah party paraded through Gaza. The apparent show of strength is stoking fears of a showdown between the heavily-armed groups. It has also highlighted the growing power struggle between Haniyeh and Abbas, who responded to the Hamas deployment by boosting the number of Fatah-loyal police on the streets of Gaza. Five rival gunmen have been killed so far this month. Analysts fear the friction between the forces could lead them to a more serious conflict.