June 17 (Reuters) - Gold edged higher on Wednesday, extending gains for a fifth straight session, as optimism around the U.S.-Iran peace deal eased concerns over interest rate hikes, while investors awaited further details on the deal and the Federal Reserve's policy meeting.

FUNDAMENTALS

* Spot gold XAU= was up 0.4% at $4,348.93 per ounce, as of 0107 GMT. U.S. gold futures GCcv1 for August delivery rose 0.3% to $4,368.40.

* Details began to emerge of the U.S. and Iran's interim agreement to end the war in the Middle East, with U.S. President Donald Trump saying it will rule out a nuclear weapon for Tehran and a U.S. official saying it allows Iran to sell oil upon signing.

* The memorandum of understanding signed this week, though yet to be made public, extends a tenuous ceasefire announced in April by another 60 days to allow the warring countries to negotiate a permanent truce.

* Investors now await the Federal Reserve policy decision and remarks, the first under Chair Kevin Warsh, later in the day, with rates widely expected to remain unchanged.

* A majority of Fed policymakers now feel they will need to keep U.S. short-term borrowing costs on hold all year, projections due out on Wednesday are expected to show, with a small number seen penciling in a rate hike to stop a spike in inflation from getting entrenched in the economy.

* A record 45% of the reserve managers surveyed by the World Gold Council expect to increase their own institutions' gold holdings over the next 12 months, the international organization said on Tuesday.

* Spot silver XAG= rose 0.4% to $70.47 per ounce, platinum XPT= gained 0.9% to $1,819.45, and palladium XPD= was up 0.6% to $1,360.32.