The summit was opened by Bahrain's King Hamad in the absence of Saudi Crown Prince and de facto ruler Abd Allah bin Abd al-Aziz, who is boycotting the two-day gathering.
"The Saudi delegation has demanded the removal of any items relating to (Gulf) economic cooperation from the agenda unless Bahrain's free trade deal with Washington is discussed and a solution is found," a Gulf source said, requesting anonymity.
The dispute over Manama's free trade deal with Washington, which other members of the Gulf Cooperation Council (GCC) are seeking to match, has prompted Crown Prince Abd Allah to stay away.
Crown Prince Abd Allah has delegated Defence Minister Prince Sultan bin Abd al-Aziz, who ranks third in the Saudi hierarchy, to head the kingdom's delegation to the two-day year-end meeting of heads of state.
Although Saudi Arabia did not publicly state the reason for Abd Allah's decision to stay away, the snub came after Riyadh failed to sway its smaller Gulf partners from forging ahead with the free trade deals with the United States.
Aljazeera's correspondent in Bahrain, Ali al-Dhifairi, said: "The absence of Saudi Crown Prince in the summit is the main point to be discussed now.
"His absence represents a clear Saudi protest against this issue.
Defence Minister Sultan bin Abd
al-Aziz (R) led the Saudi group
"Observers say there are many economic issues to be discussed in this summit, therefore, reducing the Saudi representation will affect the implementation of these issues a great deal.
"Some observers have been speculating about the outcome of these meetings, focusing on the effect the Saudi boycott would have on the summit".
Individual US pacts
Bahrain, the summit host, in September became the first member of the Gulf Cooperation Council (GCC) to sign a free trade agreement with Washington.
Ali al-Dhifairi, Aljazeera's correspondent in Manama said: "The meeting of foreign ministers on Saturday did not tackle political issues. It focused mainly on economic policies, particularly the agreements signed by GCC countries and the US under Saudi protest.
"There is a huge dispute among GCC countries, as some of them, other than Bahrain, will also sign economic agreements individually."
The Saudis say the US free trade
pact undermines Gulf solidarity
Bahraini Information Minister Nabil al-Hamr said on Sunday four fellow GCC members were involved in negotiations with the United States to conclude similar deals, leaving Saudi Arabia as the only member of the alliance not engaged in such talks.
Undermining Gulf solidarity
"Saudi Arabia believes these countries should hold group negotiations. Bahrain, however, says this issue does not negatively affect, but may even serve other Gulf states," al-Dhifairi said.
Riyadh is the only one of the six which is still not a member of the World Trade Organisation.
It has accused its Gulf neighbours of weakening Gulf solidarity by forging separate economic and security agreements with foreign powers.
In addition to Bahrain and Saudi Arabia, the regional bloc groups Kuwait, Oman, Qatar and the United Arab Emirates.
Bahrain believes US trade pacts
serve Gulf interests
Economic issues, including steps towards regional integration were expected to figure high on the summit's agenda amid concerns that the dispute over the free trade accords could jeopardise the Gulf states' fledgling customs union launched in January 2003.
The Gulf monarchies, whose combined GDP stood at $385.4 billion in 2003 and is expected to reach $421.5 billion this year, plan to establish a monetary union in 2005, a common market in 2007 and a single currency by the start of 2010.
Bahrain said on Sunday that the Gulf leaders would also look into a proposal to reduce the massive presence of expatriates, currently estimated at 12 million out of a total population of 35.8 million in the six GCC states, who increasingly regard them as a demographic and cultural threat.
The expatriates, mostly Asian workers, annually remit $27 billion to Asia alone, Bahraini Labour Minister Majid al-Alwi said.
One of the recommendations put to the summit is to "limit the stay of expatriates (in the Gulf monarchies) to four or five years," he said.
The Gulf leaders are also due to discuss efforts to combat extremism in the region.
The Gulf summit will discuss regional questions, chiefly Iraq, but four rights groups reminded the leaders on the eve of their gathering that they should also give equal attention to internal political reforms and their citizens' human rights.
In a message to the heads of state, the organisations - from Kuwait, Bahrain and the UAE - demanded "the upholding of human rights principles and the acceleration of political and constitutional reforms".
They said reforms should include holding free and fair parliamentary elections with the participation of women, and allow for the formation of political parties.
Rights groups are calling for the
acceleration of poltical reforms
The groups also demanded the protection of human rights activists and the release of all prisoners of conscience jailed in Gulf Arab states.
The point was driven home again on Monday by newspapers in Bahrain, which is a step ahead of its partners on reforms. Leader writers called on Gulf leaders to heed their peoples' interests and give them a greater role.