"Russia in Chechnya is acting in accordance with international civilized norms," President Yeltsin told reporters as he arrived in Istanbul for the meeting of the Organisation for Security and Cooperation in Europe (OSCE), which opens on Thursday.

"I'm sure they will finally understand that after my speech at the summit," he said.

BBC diplomatic correspondent Barnaby Mason analyses Russia's war of words

He said Russia would back the Charter on European Security (CES), which is due to be signed at the summit, provided no last-minute changes are made to the document.

"If it is as agreed before, then yes, we'll support it," he said.

Russian Foreign Minister Igor Ivanov, who is also in Istanbul, reinforced President Yeltsin's stand.

"If any country tries to politicise the problem (of Chechnya), to use it against us, it would become very difficult to have a constructive atmosphere at the summit," Mr Ivanov said.

Vollebaek: Appealing for dialogue

At the same time, another member of the delegation - Russian Emergency Affairs Minister Sergei Shoygu - promised that the nearly 200,000 Chechen refugees who have fled Russia's military offensive would be allowed to return to their homes by next February.

Mr Shoygu told a news conference that half of the refugees would return to what he called "liberated areas" of the rebel Caucasian republic by Christmas Day.

The BBC's Andrew Harding reports: "Russian forces are pushing deeper into Chechnya"

OSCE chief Knut Vollebaek warned: "There is no doubt that the question of the situation in Chechnya will cast a shadow over the summit."

"I want to repeat my appeal to Russia to enter into a dialogue aimed at a political solution."

Russia is engaged in a seven-week military offensive in the breakaway republic, which it accuses of harbouring separatist Islamist guerrillas. It has rejected OSCE offers to mediate.

Test ban treaty

The BBC's Barnaby Mason: Most Western leaders do not agree with President Yeltsin that Chechnya is an internal affair

US President Bill Clinton, who is also in Turkey for the meeting, said he too would urge Mr Yeltsin to seek a political solution to the conflict in Chechnya.

The two men are due to meet for talks on Thursday.

President Yeltsin announced on arrival in Istanbul that he had signed a draft law approving the Comprehensive Test Ban Treaty and sent it to the Russian Duma for ratification.

The US Senate dealt President Clinton an embarrassing blow last month by refusing to ratify the treaty.

President Yeltsin said he would urge all nations to follow Russia's example.

Military muscle

Russia flexed its military muscle on the eve of the summit, when the Russian Arctic Fleet test-fired two ballistic missiles from a nuclear submarine in the Barents Sea.

Moscow considers Chechen fighters to be "terrorists"

The warheads successfully hit their targets on the Kamchatka Peninsula in Russia's Far East, the Navy's press service said.

Russian military opposition to any outside meditation in the Chechen conflict was underlined by the chief of the Russian airforce Anatoly Kornukov.

"We are restoring order in our own country and no one has the right or will stop us from doing so," he told a press conference in Moscow.

"Russia is not Iraq, it is not Yugoslavia, and any attempt at interference will be resolutely blocked," he said.

Key accords

The OSCE is concerned about the plight of Chechen refugees

The Istanbul meeting hopes to tie up two key accords: a revised version of the 1990 Conventional Forces in Europe (CFE) treaty, and the new Charter on European Security, which is aimed at formalising Europe's post-Cold War security structure.

The new CFE accord will cut by an average 10% ceilings established in the 1990 accord for deployment of weapons such as tanks, aircraft and artillery forces, notably on front lines between the former enemy blocs.

Mr Vollebaek confirmed that the text of the amended CFE treaty itself had been agreed, but said that an accompanying political declaration "is still under discussion".

He also confirmed that "intensive discussions" were continuing even as the summit officially opens.

Contentious CES issues include definition of "the conditions required to approve use of force, including the role of the UN Security Council, and also the role of the OSCE in internal conflicts", Mr Vollebaek said.