Western criticism of Russia's military offensive in Chechnya is gradually hardening ahead of the European security summit in Istanbul from 18 to 19 November.

President Clinton says there will have to be a political solution in the end and is pressing for civilian casualties to be minimised. But the public statements of Western governments remain restrained.

The most pointed criticism so far came from the US State Department, and even that was carefully worded.

Spokesman James Rubin said the indiscriminate use of force was not in keeping with Russia's obligations under the Geneva Conventions and a Code of Conduct drawn up by the Organisation for Security and Co-operation in Europe (OSCE).

That is particularly relevant given the approaching OSCE summit.

The Russian Prime Minister, Vladimir Putin, rejected the charge. He said Russia's actions were wholly appropriate in view of the threat from armed groups trained and financed from abroad.

Mr Clinton's comments were milder than the state department's - and he himself gave one hint why that was.

"No country," he said, "wants to be seen as giving into pressure from another country. But I think they are listening."

Subtle diplomacy

Western officials argue that if you want to influence the Russians, loud public criticism is the least effective way. If you put your points strongly in a private dialogue, they say, you have a much better chance of having an impact.

So, UK diplomats emphasise that in various high-level contacts over the past two weeks, concern has been expressed at what they call the appalling civilian casualties in Chechnya and the suffering of refugees, and at the lack of a Russian political strategy.

The diplomats say behind-the-scenes pressure has persuaded Russia to give international agencies some limited access to the north Caucasus.

Other arguments are advanced in favour of the West treading carefully.

Russian parliamentary elections are looming in December, as are key economic decisions.

Western governments acknowledge that Chechnya is part of Russia, although it escaped from Moscow's control in the mid-1990s. They agree that Russia has a genuine problem of security and terrorism.

Russia is not Serbia

Some of this amounts to saying that Russia, unlike Serbia, is just too big and important to pick a quarrel with.

But Western officials reject any analogy with the Kosovo crisis. Despite the desperate refugees on Chechnya's borders, they say there is no evidence of a deliberate Russian policy of ethnic cleansing.

However, in another sense, Nato's own military action over Kosovo may be inhibiting western condemnation of Moscow. The Russians accuse the West of double standards in showing little interest in the suffering in Serbia caused by Nato bombing.

All these reasons for a muted western reaction to Chechnya will not prevent a confrontation of sorts at the OSCE summit.

The French Foreign Minister, Hubert Vedrine, said they were preparing to put pressure on Russia to recognise that there was a Chechen problem that went far beyond the issue of terrorism and should be resolved politically.

The OSCE - a lever for the West

In fact, Western governments are trying to use the summit as a lever or deadline to extract some concession from the Russians.

The promised attendance of President Yeltsin makes some kind of deal at once more likely and more unpredictable. Russia has consistently championed the OSCE as the supreme European security organisation, an argument the West does not accept.

The potential embarassment is made greater by the fact that the summit is due to witness the signing of a revised CFE Treaty, which sets out the limits on conventional forces in Europe.

Russia has admitted that its deployment of tanks and artillery in Chechnya breaches the provisions of the treaty, both in its original 1990 form and in the proposed new version.

The summit is also due to conclude a European Security Charter defining the OSCE's role in the next century. Here too, to go ahead with the signing while Russian forces pound towns and villages in Chechnya looks bad, if not farcical.

Some observers believe Russia will contrive at least a lull in the fighting while the Istanbul conference takes place.