MOSCOW, July 15 (RIA Novosti) - Russia imposed temporary restrictions on meat imports from eight countries as of July 15, following the discovery of banned substances, the national agricultural regulator said on Tuesday.

Restrictions applying to specific companies in Denmark, France, Germany, Italy and Spain come into force on Tuesday, while restrictions on companies in Australia, Argentina and Brazil apply from July 21.

The regulator has also stepped up monitoring of several U.S. poultry exporters after laboratory tests showed the presence of heavy metal salts in the firms' products.

Earlier this week, media reports said the Russian government was considering a ban on meat imports above the existing quotas as a measure to protect domestic producers. Analysts say the move would send domestic meat prices up.

The quota for meat imports in 2008 stands at 445,000 metric tons. European Union states are the main suppliers to Russia. About 300,000 metric tons of meat was supplied to the country above the quota in January-May 2008, according to the National Meat Association.