* New group says carried out Cairo bombings
* Army says roadside bomb defused in Sinai
* Police say seize bombs in raid outside Cairo (Adds arms cache seized, bomb defused in Sinai)
CAIRO, Feb 8 (Reuters) - A new militant group has claimed responsibility for two bombings in Cairo that targeted the Egyptian police on Friday and has vowed to carry out more attacks, underscoring the risk of a widening campaign of violence against the security forces.
The group - Ajnad Misr, or Soldiers of Egypt - said it carried out the attack that wounded six people in a statement posted on a Facebook page set up in its name. The statement was quoted by a website used by militant groups and by SITE Intelligence group, which monitors such sites.
Shootings and bomb attacks targeting the security forces have become commonplace since last July, when the army deposed president Mohamed Mursi of the Muslim Brotherhood following mass protests against his rule.
The state has declared the Brotherhood a terrorist group. The Brotherhood says it is committed to peaceful activism.
While many of the attacks have occurred in North Sinai - where the military said on Saturday it had defused a roadside bomb planted to target army personnel - attacks have become increasingly regular and lethal in the Nile Valley and Delta.
In a raid outside Cairo, the Interior Ministry said police seized an arms cache including 10 bombs stored at an apartment by a member of the Muslim Brotherhood, which denies government accusations it is behind the violence.
Ajnad Misr emerged late last month, claiming responsibility for six attacks at the end of January, according to SITE. "(The security forces) are not safe from retaliation which is pursuing them," its statement said.
"Our attacks on them will continue all the while their crimes continue," the statement said.
Many of the attacks have been claimed by Ansar Bayt al-Maqdis, a group based in North Sinai that has turned its attention from Israel to the Egyptian government since Mursi's overthrow.
The army-backed authorities have cracked down hard on Mursi's Islamist sympathisers since his removal. Hundreds of his supporters were killed during protests in the weeks after his removal and thousands more were arrested.
Several hundred members of the security forces have been killed in bombings and shootings since then.
The Interior Ministry said one of the bombs seized in the raid on the apartment outside Cairo in 6th of October City, 30 km (19 miles) from the capital, weighed 25 kg (55 pounds) and was equipped with timers and remote controls. The other nine were described as primitively assembled.
A suspect had confessed to belonging to the Muslim Brotherhood and said he had received the arms from a member of the group's political party, the Interior Ministry said.
The Brotherhood, most of whose leadership is in jail, has denied such accusations in the past. (Writing by Tom Perry; Editing by Janet Lawrence)