MOSCOW, April 30 (Reuters) - Investors from China and Singapore have increased holdings of Russian OFZ treasury bonds in the past few months though the overall share of foreign investors is likely to decline further amid sanction risks, a central bank official said. Elizaveta Danilova, head of the central bank’s financial stability department, said in an interview with Bloomberg published on the bank’s website that the share of non-residents among OFZ bond holders slipped to 18.8% as of April 21. This level is the lowest since mid-2015 and implies a further decline in foreigners’ share in OFZ bonds from 20.9% seen on April 1. Danilova said the central bank expects non-residents’ share to gradually decline further, though it was unclear whether their nominal holdings will also shrink. The share of Chinese investors among OFZ holders rose by two percentage points to 4% in the six months to April, while the share of those from Singapore increased by one percentage point to 7%, according to Danilova. Major Russian banks, such as Sberbank and VTB , have recently been the main buyers of OFZ bonds that Russia uses to plug budget holes, and that proved to be popular among foreign investors for their lucrative yields. The share of foreign investors has been on the decline for months and is expected to slip further after Washington barred U.S. banks from buying Russian state debt directly from Russia from mid-June. The amount of OFZ treasury bonds that Russian banks hold is low and would still be considered low if they bought all the bonds currently held by non-residents, Central Bank First Deputy Governor Ksenia Yudayeva said on Wednesday. (Writing by Andrey Ostroukh Editing by Mark Heinrich)