Asian stocks declined for the first time in a week, after credit ratings agency Standard & Poor (S&P) placed 15 Euro nations on review, for a possible downgrade.

The agency warned authorities on Monday that it could downgrade the AAA rating on Germany and five other European countries with sterling debt ratings as a result of deepening sovereign-debt crises, according to a Financial Times report. Meanwhile, there has also been speculation of a downgrade of the French economy.

The suggestion that the German economy could face a ratings cut has come as a surprise; its economy has been considered, up until now, one of the strongest in Europe.

In addition, a recent report from the Asian Development Bank (ADB) has indicated economic growth in emerging East Asian countries will continue to slow down into 2012, as growing sovereign debt problems in Europe and an anemic American economy raise the specter of a deep global economic downturn.

All Asian stock indices are trading in the red with stocks in Japan, Hong Kong and Seoul declining by more than a percent. Japanese benchmark, Nikkei, declined 1.33 percent or 115.90 points to 8,580.08. Shares of Unitika plunged 6.52 percent and Tokio Marine Holdings fell 3.79 percent, whileToshiba Corp. declined 2.56 percent. Hong Kong's Hang Seng declined 1.63 percent and the Chinese Shanghai fell 0.54 percent, while Seoul composite lost 1.3 percent.