WASHINGTON, June 28 (Reuters) - U.S. President Joe Biden, in a call with Colombian President Ivan Duque on Monday, expressed U.S. support following an attack last week on Colombia"s presidential helicopter, the White House said in a statement. Biden "reaffirmed the enduring partnership between the United States and Colombia," it said. Biden also voiced support for the rights of peaceful protesters and underscored that law enforcement "must be held to the highest standards of accountability," the statement said. Protests against Duque"s government exploded at the end of April in opposition to a now-withdrawn tax reform. While largely peaceful, they have been marked by occasional violence and clashes between police and protesters. The helicopter carrying Duque and other top officials was struck by multiple bullets on Friday while it was flying through Colombia"s Catatumbo region, Duque said in a video message after the incident. read more