COLOMBO (Reuters) - Hundreds of protesters demanding the release of defeated presidential candidate Sanath Fonseka clashed with Sri Lankan police on Sunday in a fourth day of street protests. Police had to baton charge to disburse the crowd, said police spokesman Prasanth Jayakody, adding that three police officers were admitted to hospital with minor injuries. Tensions have risen on the island since the former army commander was arrested on Monday by military police on charges of engaging in politics against his president while still in uniform. The majority Buddhist nations influential clergy, including custodians of the holiest shrine the Temple of The Tooth also appealed to President Mahinda Rakapaksa to release Fonseka. We cannot approve the arrest of Gen. Fonseka and other army personnel who were with him. They have risked their lives to eliminate terrorism and played a major role in creating peace, they wrote in an open letter to the president. It is difficult to promote peace and ensure democracy and good governance when there is a rift between the president, the defence secretary and former army chief Fonseka, they said. The former army general and Rajapaksa worked together in ending a 25-year war against Tamil Tiger separatists last year, but fell out soon after. The government said Fonseka had conspired against the president and would face court martial. On Wednesday at least eight people were injured when thousands of protesters clashed with govt supporters before police dispersed them using tear gas. On Thursday police used batons to disperse hundreds of Fonseka supporters. Fonseka, defeated in the Jan. 26 presidential poll, accused president Rajapaksa of rigging the vote. His supporters said they would seek legal action over the vote. The government has not yet detailed what charges Fonseka will face, but Rajpakasa has said he was plotting a coup. The United Nations, European Union and the United States have raised concerns over unrest in the island and urged the government to respect the law.