President Barack Obama will travel to the United Kingdom and Saudi Arabia in April, a visit set to be dominated by doubts over Britain’s EU membership and concerns about turmoil in the Middle East.

President Barack Obama will travel to the United Kingdom and Saudi Arabia in April, a visit set to be dominated by doubts over Britain's EU membership and concerns about turmoil in the Middle East.

The White House said Obama will visit Windsor Castle -- where he will have a private lunch with Queen Elizabeth II -- and 10 Downing Street for a joint press conference with Prime Minister David Cameron.

His visit comes ahead of Britain's hotly contested June referendum on European Union membership.

Obama is likely to express his strong backing for keeping Britain in the EU, but will have to rebuff allegations of interference.

London's mayor Boris Johnson -- a chief proponent of leaving the bloc -- has accused Obama of "exorbitant hypocrisy" given America's "hysterical vigilance" about its own sovereignty.

In Saudi Arabia, Obama will attend a summit of the Gulf Cooperation Council, were Washington's policies toward the Middle East are likely to come under the microscope.

Uneasy partners in the Gulf have been furious at Obama's engagement with Iran and perceived retreat from the Middle East.

A senior Saudi royal has publicly criticized Obama for comments accusing the longtime U.S. ally of feeding Middle East conflicts.

Saudi Arabia, the world's top oil exporter, has long been a major ally of the United States but the relationship has deteriorated under Obama.

In an opinion piece published in Saudi newspapers, Prince Turki al-Faisal, the kingdom's former intelligence chief and envoy to Washington, lashed out at Obama's recent comments to The Atlantic magazine.

During the visit Obama will also visit Germany, and, according to the White House attend "Hannover Messe – the world’s largest trade show for industrial technology – and meet Chancellor Angela Merkel."