Today, the group Mujahedeen Egypt posted a claim on the Internet and said it had targeted Jewish vacationers. The site gave the names of five persons who allegedly died carrying out the attacks.
Earlier, an Al-Qaeda-linked organization and a previously unknown group had claimed responsibility.
Meanwhile, police are focusing on six Pakistani men who disappeared from a hotel in Sharm El-Sheikh and left their passports at the hotel's reception desk.
Police are circulating photographs of the six men in and around the southern Sinai resort city. An Associated Press correspondent who saw the images said the men appeared to be between 20 and 30 years old.
It is not clear yet if the men have any connection with the bombing. It is also not known in which hotel they were staying.
Jeremy Binnie is a Middle East analyst with Jane's "Sentinel" in London. He says it is difficult to determine the motive behind the attacks in Egypt.
"People were looking at timelines, saying this is seen after the London attacks, maybe this is some sort of counterattack against the West," Binnie told RFE/RL. "This, what is going on at the moment, is some sort of surging Al-Qaeda-related violence. And Sharm El-Sheikh is where a lot of rich people go and you have this Pakistani connection again coming through."
On the surface the Egyptian authorities seem to have taken resolute measures aimed at securing the area and searching for the suspects.
However, Binnie says the Egyptians implemented many of the same measures following a terrorist bombing last year in Taba -- without any discernable effect.
"[After the Taba bombing,] there were extensive sweeps and arrests and people were held for ages," Binnie said. "They were trying to neutralize the threat to the tourist industry on the Sinai Peninsula."
Sharm El-Sheikh is one of Egypt's best-known resorts. It has hosted summits between Israeli and Palestinian leaders and many foreigners, including Israelis, vacation there.
The effects of the attacks on a local economy are predictable and are likely to be drastic and instantaneous. Egypt's $7 billion-a-year tourism industry plays a huge role in the country's economy.
Others say the bombing might have been an attempt to destabilize Egypt in the run-up to the first-ever competitive presidential election due on 7 September. Egypt is an ally of the United States and gets substantial American financial assistance.
Egypt: Authorities Launch Manhunt After Resort Bombings