Middle East Correspondent Jim Muir: "Deep alarm in the Arab world"

The Turkish government is awaiting the arrival of President Hosni Mubarak of Egypt, who has already visited Damascus in an effort to mediate between Turkey and Syria.

President Assad of Syria has already made his views known to Hosni Mubarak

Turkish officials say they welcome President Mubarak's mediation efforts because they want international attention focused on Syrian support for the PKK. They also want a diplomatic solution to the problem.

Turkey presented a series of proposals for a new start with Syria three months ago, but officials say they have not received a reply from Damascus.

The BBC's Ankara correspondent, Chris Morris, says the Syrians have their own complaints about Turkish behaviour, but it is the government in Ankara which has decided to raise the stakes in a relationship which has never been easy.

The Turkish military is particularly frustrated by Syrian support for the PKK. Every time the military says the rebel movement is on the verge of defeat, the war drags on.

Our correspondent says the generals want someone to blame and Syria is as good a candidate as any. If Syrian policy does not change, some elements in the Turkish military may well believe the only solution is to stage operations against the PKK inside Syrian territory, using air strikes or even ground troops, like they do on a regular basis in Kurdish-controlled Northern Iraq.

A decision to do that would shake the entire region, which is why the Turkish foreign ministry appears more cautious - but politicians from all parties have made it clear that Turkey's patience is wearing extremely thin.

Middle East analyst Roger Hardy explains why the dispute has become a regional issue

Relations between Turkey and Syria deteriorated dramatically on Thursday, when the Turkish President, Suleiman Demirel, warned Damascus that patience was running out over alleged Syrian support for Kurdish separatists.

Syria, for its part, is critical of Turkey's military ties with Israel, and has accused Turkey of taking more than its share of water from the Euphrates River.

There have been fears the tension between the two countries, who share a 877km (550 mile) border, could lead to military confrontation.

The head of the Turkish armed forces, General Huseyin Kivrikoglu, has described the situation as an undeclared war, but both sides insist they want a diplomatic solution.

"I am ready to do everything possible in Damascus and Ankara [to reduce the tension]," Mr Mubarak told reporters on Saturday, after a visit to Saudi Arabia, where he discussed the crisis with King Fahd.

Israel moves to calm situation

Israel says its strategic ties with Turkey are not directed at Syria or any other country.

A statement by the Defence Minister, Yitzhak Mordechai, said Israel was not looking for a conflict with Damascus. Mr Mordechai has ordered the army to adopt a low profile on the Syrian border.

General Huseyin Kivrikoglu - "undeclared war"

On Sunday, the Turkish Deputy Prime Minister, Bulent Ecevit, said his country wanted a peaceful resolution to the crisis.

"Turkey ... is working to solve all its problem with Syria through peaceful means and diplomatic channels," Mr Ecevit was quoted as saying.

"But Turkey cannot not make even the smallest concession on its rights and security," he said.

On Friday, Turkey sent some 10,000 soldiers into Iraq to attack Kurdish rebels there, and there have been reports that Turkey is considering a similar incursion into Syria.

Growing tension

The growing tension between the two countries has provoked accute concern in the Arab world.

The BBC middle east correspondent says President Mubarak is well-placed to mediate because he has maintained good relations with both countries.

President Mubarak enjoys good relations with Syria and Turkey

While he has been forthright in his criticism of Turkey's military ties with Israel, he has kept on good terms with Ankara.

Mr Mubarak has also managed to cultivate warm relations with Syria despite Egypt's own truce with Israel.

Egypt is particularly concerned about the dispute because it feels a strong responsibility towards the Middle East peace process.

Mr Mubarak has already conferred with President Assad of Syria over the tension with Turkey, and Damascus has issued a statement stressing its concern for good, neighbourly relations with Ankara, and its readiness to settle differences by diplomatic means.

Turkey too, while adopting an increasingly threatening tone, has said it wants a diplomatic solution.