Foreigner can be mortgagee in real estate mortgage

Dear PAO,

My brother-in-law is a foreigner who lent a substantial amount of money to my uncle. In order to secure his interest, he would like to demand the execution of a real estate mortgage (REM). However, he was informed that there is a prohibition on aliens from acquiring lands in the Philippines. Thus, he was told that he couldn’t be a mortgagee since one of the possible consequences of an REM is the conduct of a forced sale. Despite the unsolicited advice, in order to be certain regarding the matter, we would like to know if indeed a foreigner is not allowed to be a party mortgagee in an REM concerning a real property situated in the Philippines.