KARACHI (Reuters) - Pakistans foreign exchange reserves fell to $16.56 billion in the week ending July 23, from $16.70 billion a week ago, the SBP said on Thursday. Reserves held by the State Bank of Pakistan (SBP) fell to $12.77 billion from $12.86 billion a week earlier, while those held by commercial banks also fell to $3.79 billion from $3.84 billion, said Syed Wasimuddin, the SBPs chief spokesman. Pakistans forex reserves rose to a record high of $16.77 billion in the week ending July 2, thanks to foreign inflows worth $750 million received during the week. The previous record high was $16.45 billion in October 2007. In May, Pakistan received $1.13 billion, the fifth tranche of a $10.66 billion International Monetary Fund (IMF) loan. The IMF loan package was agreed to in November 2008 to help avert a balance-of-payments crisis and shore up reserves.