The Vatican will host a celebration on May 2 at the Pontifical North American College in Rome to garner support for Rev. Junipero Serra, a missionary who is expected to be canonised later this year.

Serra was instrumental in converting Native Americans to Christianity during the 18^th century, but his actions were considered genocide by some critics.

The celebration is presented by the archdiocese of Los Angeles, the College, and the Vatican, and Pope Francis will officiate Mass in Rev. Serra's honour.

Serra travelled through California with the Spanish conquistadors, and is accused of aiding in the infection, murder, enslavement, and persecution of Native Americans in the area. Demonstrators in California have protested his impending canonisation, and have called for the missionary's statue to be removed from Congress' National Statuary Hall.

The Vatican has defended Rev. Serra, saying that he used corporal punishment as a disciplinary method, but helped prevent more violent acts against the natives.

"It is not to be excluded, but it wasn't 'genocide,' it wasn't a death penalty," a Vatican saint-making office official, Rev. Vincenzo Criscuolo, told reporters. Pontifical commission for Latin America leader Guzmán Carriquiry also criticised the push to remove the only person of Spanish descent from the Statuary Hall.

"They want to remove him from the Capitol precisely when the first Hispanic pope is planning to canonise him," Carriquiry said. "Let's say that it would not be an extraordinary welcome from a country that claims to be an example of multicultural welcomes."

Serra is scheduled to be canonised during Francis' trip to the United States this fall. The ceremony will take place at the National Shrine in Washington DC on September 23. Francis announced in January that Serra will be canonised, although a second miracle attributed to Serra's intercession has not been confirmed.