Tens of thousands of people are marching in Mexico City in opposition to Mexican President Enrique Pena Nieto's push to legalize same-sex marriage.

A much smaller demonstration by supporters of same-sex marriage also took place. The two sides were kept apart Saturday by hundreds of police and barriers erected around the city's iconic Angel of Independence monument.

Representatives of the National Front for the Family that organized the opposition march say caravans of buses arrived from several states around the country.

Demonstrators dressed all in white carrying white balloons filled a wide boulevard for many blocks.

In May, Pena Nieto proposed legalizing same-sex marriage nationwide. It is legal only in some places including Mexico City and the northern state of Coahuila.

The Roman Catholic church opposes the president's proposal.