"The second thing is the Fed meeting today and tomorrow ... and as long as the Fed is unclear with the timing of the rate hike, that's a good environment for gold," ETF Securities' Arnold said.
Gold is sensitive to interest rates changes, with increases mostly signaling a rise in the opportunity cost of holding the non-interest yielding metal.
The Bank of England, Swiss National Bank and the Bank of Japan will also meet this week, and are expected to hold monetary policies steady given caution about the global economic outlook.
"The risk of Britain leaving has now increased substantially and the Fed will therefore signal its willingness in no uncertain terms to 'stay the course' (keep rates unchanged) in light of this potential 'Black Swan' event," INTL FCStone analyst Edward Meir said in a note.
In other news, the Hong Kong Exchanges and Clearing is aiming to launch its planned physically-delivered gold futures contract in September, its head said on Tuesday.
Holdings in SPDR Gold Trust, the world's largest gold-backed exchange-traded fund, rose 0.27 percent to 896.30 tonnes on Monday, the highest since October 2013.
Silver futures fell 0.13 percent to $17.42 per ounce, after touching a one-month high of $17.48. Platinum futures was down percent at $975.30 while palladium fell 2 percent to $534.70.