Foreigners' share of OFZ bondholdings has already exceeded 25 percent and may rise towards 2018 highs of 34.5 percent, Nabiullina told a news conference on Friday on the sidelines of the IMF and World Bank spring meetings in Washington.
Demand for the rouble-denominated bonds is seen as a gauge of global market sentiment towards Russian assets.
A rise in foreign holdings supports the rouble and helps the finance ministry fulfil its borrowing plan, while an outflow of foreign funds would dent the currency and other Russian assets, as was the case in 2018.
The higher the share of foreigners among holders of OFZ bonds, the deeper the possible negative impact on Russian markets should foreigner investors decide to ditch Russian paper.
However the current high proportion of foreigners holding the bonds is causing little concern in Moscow thanks to Russia's low overall debt burden, Nabiullina said.
She said the central bank's aim was to minimise the impact of Western sanctions against Moscow, particularly possible sanctions on those who hold Russian bonds.
The United States has been threatening for months to slap sanctions on Russian debt for what it calls Moscow's "malign activities", but it has not taken any real steps against Russia's ability to borrow.
"If external developments take place ... we have a full toolkit and we are ready to use it," Nabiullina said.
(Reporting by Trevor Hunnicutt in Washington and Elena Fabrichnaya in Moscow; Writing by Andrey Ostroukh; Editing by Jan Harvey)
