More than 2.5 million Muslim pilgrims began on Friday the rites of the annual hajj pilgrimage, leaving the holy city of Mecca for Mount Arafat, where the prophet Mohammed is believed to have delivered his final hajj sermon.

Dressed in white, they flooded the streets as they headed towards Mina, around five kilometers east of the holy mosque.

Saudi authorities have released six Shiites detained after protests in the Eastern Province last spring, bringing to 23 those released in two days, activists said on Thursday.

All those freed come from the Shiite area of al-Qatif.

Saudi Crown Prince Nayef bin Abdul Aziz on Tuesday noted that U.S. allegations of Iranian involvement in a plot to murder the Saudi ambassador to Washington did not "require an agreement" with Tehran concerning its hajj pilgrims, Agence France Presse reported.

AFP quoted the prince earlier on Tuesday as saying that "there can be no compromise with Iran concerning the assassination bid because there is no need for it." However, the agency later corrected that version, noting that it had misinterpreted the crown prince’s remarks.

Saudi authorities have released 17 Shiite activists detained in anti-government protests earlier this year, but dozens more were still in jail, activists said on Tuesday.

"Some of the released detainees have already returned to their homes while others are finalizing their release papers," a human rights activist told Agence France Presse on condition of anonymity.

Qatar's Prime Minister Sheikh Hamad bin Jassem al-Thani proposed on Sunday that Saudi and Iranian officials should meet over the alleged Iranian plot to kill the Saudi envoy to Washington, state media said.

"I think that the best and easiest way to solve this issue is for the two sides to meet," Sheikh Hamad, who also holds the foreign affairs portfolio, said after meeting Iranian Foreign Minister Ali Akbar Salehi, QNA state news agency said.

A Saudi court on Saturday jailed for 15 years a Saudi woman known as "al-Qaida lady" for being the first woman in the kingdom tried for involvement in violence by the jihadist network, state media said.

"A Saudi woman was sentenced to 15 years in jail starting on the date of her arrest, followed by 15 years of a ban on travelling after her release," SPA state news agency reported.

Saudis began swearing allegiance on Saturday to the new Crown Prince Nayef bin Abdul Aziz, described by the local press as the "man for the job" and praised in Washington for his commitment to fight terrorism.

Nayef -- who served as interior minister for nearly four decades and led a crackdown on al-Qaida in the kingdom -- was named in a royal decree on Thursday to succeed Prince Sultan who died in the U.S. last week following a long illness and was buried in Riyadh.

U.S. President Barack Obama on Friday congratulated Saudi King Abdullah on the selection of Prince Nayef bin Abdul Aziz as his heir, noting the new crown prince's counterterrorism record.

"I congratulate King Abdullah and the Saudi people on the selection of Prince Nayef bin Abdul Aziz as crown prince. We in the United States know and respect him for his strong commitment to combating terrorism and supporting regional peace and security," Obama said in a statement.

Saudi Arabia's powerful interior minister, 78-year-old Prince Nayef bin Abdul Aziz, was named the new heir to the throne in a royal decree read out on state television Thursday.

Nayef -- who has been interior minister for nearly four decades and led a crackdown on al-Qaida in the kingdom -- succeeds prince Sultan bin Abdul Aziz, who died last week in New York and was buried Tuesday in Riyadh.

The United States should use covert action against Iran or even "kill" some of its top officials in retaliation for an alleged plot to kill Saudi Arabia's U.S. envoy, lawmakers heard Wednesday.

"I'm saying we put our hand around their throat right now in every interest they have," retired U.S. Army general Jack Keane told a hearing of the House of Representatives' Homeland Security Committee.