MOSCOW (AP): Russia's federal market regulator suspended trading on Moscow's stock exchanges Tuesday, a day after the benchmark RTS index suffered its biggest-ever one-day loss.

The order postponed the start of trading until 1 p.m. (0900 GMT), 2.5 hours after the usual opening, the MICEX and RTS exchanges said in statements.

The indexes of both the RTS and the MICEX dropped nearly 20 percent on Monday, the steepest declines ever for a market that was booming even amid growing signs of trouble in Western economies.

Since May, the RTS index has plunged 64 percent.

Russia's markets have been hit hard by the global economic crisis, declining prices for the oil that is the backbone of Russia's economy and this summer's war with Georgia.

Earlier this year, as international economic problems accelerated, Russian officials, including Finance Minister Alexei Kudrin, contended that Russia's economy would be a comparative haven of stability because of world demands for energy.

Russia's leadership has appeared slow to respond to the preciptious deterioration of the market.

In a statement Tuesday ahead of taking part in an international conference in France, President Dmitry Medvedev said ``the problems of international politics and the crisis in the international financial system demand joint and urgent actions,'' but did not give details.