COLOMBO (Reuters) - Sri Lanka's Prime Minister Mahinda Rajapaksa on Monday offered his resignation amid the island nation's worst economic crisis since independence that has led to widespread protests, a government official said.

       "The prime minister has sent his letter of resignation to the president," the official said, declining to be named.

       President Gotabaya Rajapaksa is the prime minister's younger brother.

       (Reporting by Uditha Jayasinghe, Writing by Devjyot Ghoshal; Editing by Toby Chopra)