Police in Egypt have arrested 10 people in connection with the triple bomb attack in the Red Sea resort of Dahab that killed at least 23 people.
Those arrested are Egyptian and were detained in the town.
Police are following two possible lines of inquiry, says the BBC's security correspondent Frank Gardner.
They have questioned around 70 local Bedouin, but the resort's popularity with Westerners could also point to al-Qaeda, our correspondent says.
Around 62 people were injured in the blasts on Monday evening.
The attack is the third strike against tourist resorts along Egypt's Red Sea coast in the past two years.
Officials remained unsure whether Dahab was hit by suicide bombers, or if the bombs were detonated with timers.
Some Bedouin are said to have a grudge against the government following rapid tourist development on their ancestral lands which has benefited mainly Egyptian workers imported from Cairo, our correspondent says.
But on Tuesday, local tribal leaders and holidaymakers held a peaceful march to condemn the attacks and stress support for the tourism industry.
They were joined by Egyptian Prime Minister Ahmed Nazif.
"Terrorists do not know borders any more," Mr Nazif said, pledging that Egypt would remain on the "front line" of the global war against terrorism.
A host of world leaders have condemned the attack, which followed blasts in Taba in 2004 and Sharm al-Sheikh in 2005.
Dahab's seaside promenade, crowded with popular restaurants, was hit by two blasts in quick succession at about 1900 (1700 GMT) on Monday.
A third bomb exploded in a nearby shopping street, where tourists browsed for holiday souvenirs.
The town has grown from a Bedouin village along with the influx of tourists in Sinai, but remains a small, low-key resort popular with Western backpackers, budget Israeli tourists and scuba divers.
Eyewitnesses spoke of seeing debris and body parts in the streets.
RECENT ATTACKS IN EGYPT
July 2005: Bombings in Sharm al-Sheikh kill 64
April 2005: Two attacks on tourists in Cairo, three dead
October 2004: Bombings in Taba and Ras Shitan kill 34, including 12 Israelis
Egypt's Minister of Tourism Zoheir Garana told the BBC it was too early to say who was behind the attacks.
Like other towns in the Sinai peninsula, entry to and exit from Dahab is controlled by police checkpoints straddling the only road into and out of town.
Previous investigations into bombings in Taba and Sharm al-Sheikh have focused on local Bedouin tribes, despite early suspicions that Islamist militants were involved.
The Egyptian authorities are thought to have uncovered a militant group active in the Sinai, but have said very little about it.