Oil dipped below $69 a barrel on Wednesday, falling back after U.S. industry data showed gasoline reservoirs swelled unexpectedly, despite growing geopolitical troubles in some OPEC member countries.

By 1425 GMT (10:25 a.m. EDT), U.S. crude for August delivery was down 40 cents at $68.84 per barrel. London Brent crude fell 40 cents to $68.40.

American Petroleum Institute (API) data on Tuesday showed inventories of gasoline surged 3.7 million barrels, well above the predicted 1.3-million-barrel increase, as refiners raised their utilization rates and imports rose.

The U.S. government's Energy Information Administration data on Wednesday was expected to confirm the API's view.

Analyst Olivier Jakob of PetroMatrix in Switzerland said geopolitical concerns in OPEC members Iran and Nigeria were also weighing on investors in the oil markets.

There are some real disruptions to flows in the case of Nigeria. In the case of Iran, the strife has gone on long enough to be uncomfortable. We have to remember what happened in Venezuela.

Multiple militant attacks on pipelines and oil installations in the Niger Delta recently have forced production stoppages at sites run by Agip , Chevron and Royal Dutch Shell .

Iran's deputy oil minister Akbar Torkan was sacked on Monday, and sources said he was replaced for being close to defeated presidential candidate Mirhossein Mousavi. The world's fifth-largest oil exporter is wracked with its worst civil unrest in 30 years over a disputed presidential election.

Attacks on oil installations are not a risk we would consider, but we have to keep in mind what happened in Venezuela and the impact witch-hunting had on production levels, Jakob said.

(Editing by Christopher Johnson)