Hamas militants have executed a senior Fatah commander after seizing him in central Gaza Strip on Thursday evening, sources from the Islamic movement confirmed.

Hamas media reported that Samih al-Madhoun, a local leader of Fatah's military wing in northern Gaza Strip, was seized when he tried to pass over a Hamas-run checkpoint in central Gaza Strip town of al-Nussairat.

The sources said that al-Madhoun refused to stop, opened fire at Hamas gunmen at the roadblock and killed one of them.

Hamas militants responded to the fire, killing al-Madhoun's driver and taking the commander to the house of the Hamas man who was shot dead at the checkpoint. Then they openly executed the Fatah commander at the Hamas fighter's house.

Meanwhile, Hamas has continued capturing security posts of pro-Abbas forces. In the afternoon, they took over the General Intelligence compound in a northwest Gaza city, leaving only two strongholds for Fatah.

But Hamas has unofficially gave an ultimatum for Abbas' forces to lay down their weapons and promised its supporters to hold Friday prayers at the presidential compound, one of the remaining Fatah strongholds.

Earlier in the day, Hamas fighters have stormed the Preventive Security headquarters in Gaza city and seized it in fierce clashes that left 14 people dead.

The death toll of five days of violence has risen to at least80, most of them affiliated with Fatah and other civilians.