Egyptian police arrested Wednesday four members of an Islamist militant group over bomb blasts near a presidential palace, although another group claimed it had planted the explosives.
Two bomb disposal experts, a police colonel and lieutenant colonel, were killed Monday as they attempted to defuse bombs outside the Ittihadeya palace in eastern Cairo.
Security forces "arrested four suspected of being involved in the latest blasts that happened near the presidential palace," a security official said.
They were "among the most dangerous terrorist elements of Ansar Beit al-Maqdis (Partisans of Jerusalem) and are being interrogated," the official added.
Three were arrested at dawn in the southern Cairo suburb of Helwan, while the fourth was detained in the capital's Nasr City district, he said.
Sinai-based Ansar Beit al-Maqdis has claimed some of the deadliest attacks in Egypt since the ouster of Islamist president Mohamed Morsi last July.
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But the bombs that exploded Monday were actually claimed by another group, Ajnad Misr (Soldiers of Egypt), which had warned on Friday that it had planted them.
It said then that it had not set off the bombs to avoid civilian casualties, and warned passers-by to stay away from the palace.
The authorities claim that groups like Ansar Beit al-Maqdis are linked to Morsi's Muslim Brotherhood, which was blacklisted as "terrorist organisation" in December after a deadly bombing north of Cairo.
The Brotherhood denied that bombing as well as all other attacks, saying it is resorting to only "peaceful protests" in favour of Morsi.
Attacks by militants have killed almost 500 police and soldiers since Morsi's overthrow, the government says.
Egypt marks the anniversary Thursday of Morsi's toppling.
Since then, it has been roiled by unrest, with a police crackdown killing more than 1,400 Morsi supporters. At least 16,000 others have been jailed, and about 200 sentenced to death.