The chairman of Turkey's ruling party urged President Bush today to heed popular protests against a war in neighboring Iraq, reinforcing Turkey's increasingly public opposition to a possible conflict in which the United States is pressing its NATO ally to play a key supporting role.

Recep Tayyip Erdogan, head of the Justice and Development Party, made his remarks as Turkish diplomats cemented plans for a gathering here Thursday of foreign ministers from five Middle Eastern countries -- Saudi Arabia, Jordan, Syria, Iran and Turkey -- that aims to prevent a war, in line with the sentiments of their people. Erdogan praised the peacemaking effort, which he termed part of "the most dynamic foreign policy in Turkey's recent history."

The ministers' meeting is billed as a precursor to a summit conference of the same countries next week. That meeting, which both Turkey and Syria have offered to host, would be aimed at producing a joint declaration urging Iraq's president, Saddam Hussein, toward dramatic but still unspecified concessions that might avert war.

"Turkey's efforts are being appreciated by Iraq," the Iraqi ambassador to Turkey, Talib Abid Salih, told reporters in Ankara, the Turkish capital.

However, Erdogan's warning today was directed to the West. "It is unfortunate that the people of the United States and Britain are filling city squares, demanding peace while others are in favor of war," Erdogan told a caucus of the ruling party in comments broadcast live on Turkish news channels. "The world's decision-makers must heed this rising call for peace."

Erdogan defended sending a much-criticized trade delegation to Baghdad earlier this month, proudly noting that "in the trip, deals worth about $690 million were signed." He also boasted, "For the first time, Turkey is following an agenda-setting strategy. In order for the initiatives that started as the war against terrorism not to get out of control, we make a call to the world's conscience."

Erdogan, as Justice and Development chairman, is widely regarded as the country's most powerful politician. He is expected to replace his friend Abdullah Gul as prime minister within months, following changes in Turkish law that had barred Erdogan from office because of a conviction for mixing religion and politics. Turkey, a Muslim country, is governed on strictly secular principles.

The party, which won control of almost two-thirds of parliament on a populist reform platform, had been considered more hawkish on Iraq than the coalition government it replaced. But since taking power in November, it has deferred to public opinion, which runs overwhelmingly against cooperating with any U.S.-led invasion.

Erdogan's speech was made to lawmakers who, under the Turkish constitution, would decide whether to open bases to U.S. warplanes, armor and perhaps 15,000 infantry. The precise configuration of the U.S. force is a matter of detailed "military to military" talks that on Monday brought Air Force Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, to Ankara for a visit with his Turkish counterpart.

Analysts said Erdogan's remarks would disappoint U.S. officials, who have urged party leaders to prepare the ground for a "yes" vote on the bases. Pentagon planners deem the bases crucial to opening a northern front against Iraqi forces. A growing U.S. deployment in the Persian Gulf region is preparing now to confront Iraqi troops from the south.

The conspicuous peacemaking efforts are aimed not only at the Turkish public, but also at cultivating relations with Middle Eastern neighbors often neglected under previous governments, said Soner Cagaptay, an analyst at the Washington Institute for Near East Policy.

At the same time, Turkish officials have quietly negotiated how U.S. forces might use their facilities to prosecute a war. Officials and analysts say the final details likely will be approved late next week by the National Security Council, which is dominated by Turkey's powerful general staff. The council's recommendation would then go to parliament, although the timing remains unclear. Turkish leaders insist that any military operation against Iraq could come only after a fresh U.N. Security Council resolution explicitly authorizing force.

Observers say that party discipline within Justice and Development is such that its leaders likely can produce the votes needed to open the bases, which in turn would encourage the U.S. Congress to pass an economic relief package valued at $14 billion to shore up investor confidence in Turkey, which is still deep in a recession. So far, however, the government's rhetoric has been in line with Erdogan's defiant statements today.

In the Turkish capital of Ankara on Sunday, demonstrators carry banners showing their opposition to a possible U.S. military operation against Iraq.Party leader Recep Tayyip Erdogan referred to American and British protesters "demanding peace."