LONDON (Reuters) -OPEC oil output edged lower in April despite a scheduled output hike taking effect, a Reuters survey found, led by a cut in Venezuelan supply on renewed U.S. attempts to curb the flows and smaller drops in Iraq and Libya.

The Organization of the Petroleum Exporting Countries pumped 26.60 million barrels per day last month, down 30,000 bpd from March's total, the survey showed on Thursday, with cuts by some producers offsetting higher Iranian supply.

The reduction comes despite OPEC+, which comprises OPEC and its allies including Russia, beginning in April to unwind its most recent layer of output cuts. The group plans to accelerate the hikes in May and June, citing supportive market fundamentals such as low inventories.

The full extent of the rises will depend partly on the impact of attempts by U.S. President Donald Trump to clamp down on supply from Iran and Venezuela.

The biggest drop among OPEC members in April was from Venezuela, where exports declined as cargo cancellations to U.S. oil company Chevron forced ships to return.

Iraq, which is under pressure to boost compliance with OPEC+ output quotas, also curbed output, the survey found.

There was little change in output from top producer Saudi Arabia, and in Gulf members the United Arab Emirates and Kuwait, despite higher OPEC+ quotas for April.

While the survey and March data provided by OPEC's secondary sources show the UAE and Iraq are pumping close to the quotas, other estimates, such as those of the International Energy Agency, suggest they are pumping significantly more.

Among countries pumping more, Iran boosted exports in April, the survey found, and provided OPEC's largest output hike with the latest U.S. measures having little impact on output.

The Reuters survey aims to track supply to the market and is based on flows data from financial group LSEG, information from other companies that track flows such as Kpler, and information provided by sources at oil companies, OPEC and consultants.

(Additional reporting by Ahmad GhaddarEditing by Kirsten Donovan)