Credit rating agency Standard and Poor's assured global investors Monday that its historic downgrade of the U.S. credit rating would have no immediate impact on Asia-Pacific sovereign ratings, but could have a negative impact in the long run.

S&P lowered its rating for U.S. government debt on Friday to AA+ from AAA .

In a statement, S&P said the potential longer-term consequences of a weaker financing environment, slower growth and higher risk aversion are negative factors for Asia-Pacific sovereign ratings.

Asian markets all opened from one to three percent lower Monday.