Russia will switch some crucial processes to manual control during the year 2000 changeover because it cannot afford to fix the Y2K bug on time, an official said Wednesday.

Russian deputy security chief Vladislav Sherstyuk did not say what share of Russia's computers are ready for the millennium change or how much money would be needed to prepare the rest, the Interfax news agency reported.

''For some time, certain spheres will be moved from computer-aided operation to others,'' Sherstyuk was quoted as saying.

Government officials refused to specify what processes will be handled manually, or how long it would take before they could be switched back to automatic control.

The State Communications Committee, which is in charge of Russia's preparations for the year 2000 changeover, earlier said Russia will also reduce the number of airplane flights on Dec. 31 and halt some hazardous industrial processes.

Deputy Railways Minister Viktor Semyonov said equipment has been installed to avert millennium-change problems in traffic control and ticket sales. ''During the test, all facilities operated without a hitch,'' he said, according to the ITAR-Tass news agency.

The millennium bug may occur if computers that use two figures to designate a year mistake the year 2000 for 1900 and shut down or produce erroneous information.