Mrs Putin showed Mrs Schroeder the sights

US officials said last week that Russia had moved the weapons, raising security concerns in neighbouring Poland and the Baltic states.

Mr Schroeder arrived in Moscow on Saturday to celebrate the Orthodox Christmas, as part of a visit that has been billed as private.

But his stay is likely to be dominated by the question of Russian debt repayments.

Christmas celebration

The two leaders and their wives spent Saturday at leisure, touring the Kremlin, going walkabout on Red Square and watching the ballet Giselle at the Bolshoy Theatre.

Mr Putin was seen to cross himself during the service

And they attended a Christmas service at Moscow's Christ the Saviour Cathedral, rebuilt in the 1990s after the original was destroyed by Stalin.

Mr Putin, a former KGB spy who says he was christened secretly under communism, was seen crossing himself during the service.

Interfax quoted Mr Schroeder as saying that nothing serious was discussed by the two men during the day.

However, correspondents say the two will spend much of their remaining time discussing Russia's announcement on Friday that it plans to delay its scheduled payments to the Paris Club of industrial nations.

Russia owes nearly $50bn - 40% of it to German banks.

Some reports say there are proposals to convert all or part of the debt into shares in Russian companies.

Personal ties

Both leaders insist the visit is part of an important process of strengthening their personal ties.

Putin is committed to clearing Russia's debts

BBC Russian affairs analyst Stephen Dalziel says Mr Putin's relations with Mr Schroeder are becoming almost as close as his friendship with UK Prime Minister Tony Blair.

But, while both Britain and Germany are keen to encourage greater trade with Russia, the Berlin government has a more acute economic interest in Moscow.

Germany is owed a greater share of Russia's foreign debt than any other creditor, and Russia has announced that it is unilaterally delaying payment of the next tranche of $3.5 billion, which it was due to meet this year.

Moscow insists that negotiations are in progress with the Paris Club, and that this is not a default on its payments.

But amid the personal camaraderie, Mr Schroeder will be looking for some indication from Mr Putin that this is merely a temporary setback.