LONDON, March 3 (Reuters) - Tax hikes announced in finance minister Rishi Sunak’s budget on Wednesday will take Britain’s tax burden to its highest since the 1960s midway through this decade, the independent Office for Budget Responsibility said. “The tax rises announced in this Budget increase the tax burden from 34.0% to 35.0% of GDP in 2025-26, its highest level since Roy Jenkins was Chancellor in the late 1960s,” the OBR said in its latest economic outlook. Over half of this rise comprises an increase in the rate of corporation tax to 25% from 19% from 2023, the OBR said. (Reporting by Andy Bruce; editing by Michael Holden)