An explosion in the main sewerage plant of a southern Russian city last week has caused 500, 000 cubic meters of untreated waste to flow daily into the river Don.


Officials said Monday that if the Rostov-on-Don station was not repaired within two weeks, a serious ecological catastrophe could result.


The head of the city's waste containment committee, Ivan Stanislavov, said the situation was not yet critical, but feared the worst if repairs were not successful.


"I'm not a specialist and cannot foresee the outcome", Stanislavov


said but we must work around the clock to repair the damage as soon as possible".


The reason for the accident is not Clear, he said, although officials said gases may have leaked and caused the explosion. Stanislavov also suggested that chemicals used by factories, which use the city sewerage instead of specialized treatment systems, might have caused the accident.


Last Wednesday's accident killed four, but residents in the neighboring city of Taganrog were reportedly not


warned about the contamination of "the river until 24 hours after the event.


For the time being, all untreated waste will continue to pour into the Don, which flows into the Sea of Azov, since no back-up system was built.


The level of damage to the pumps in the central sewerage building is the


key to how fast repairs can get underway.


The specialized equipment now lies buried under rubble from the top floors that were completely destroyed by the blast. The equipment, which took three years to install during the '60s, is now no longer being made and can therefore not be replaced, Stanislavov said.


"Although we must work quickly, we must also be very careful that the building does not collapse completely and do more damage", Stanislavov commented.


The cold weather in Rostov-on-Don, a city of 1. 8 million, has luckily eased the situation somewhat, he added. If the accident had occurred in summertime, it would undoubtedly have caused a series of epidemics.


Local drinking water is still as safe as it ever was since the reservoir supplying the area was not contaminated.


Repairs to the plant are expected to last two weeks.