A senior Egyptian opposition figure convicted of offending public morals says his verdict is payback after he won a lawsuit against the government over two Red Sea islands that Egypt had surrendered to Saudi Arabia.

Khaled Ali was widely expected to run against President Abdel-Fattah el-Sissi in next year's presidential elections. He said on Facebook that he intends to appeal. He will lose his eligibility to run in the election if the verdict is upheld.

Ali didn't attend Monday's hearing in which he was convicted of making an obscene finger gesture.

Though a court in January annulled the islands handover under a 2016 Saudi-Egypt deal, parliament later approved the pact and el-Sissi ratified it, clearing the way for its implementation.

Saudi Arabia is a major financial backer for Egypt.