Currently a member of the House of Representatives, the lower chamber of the country's parliament, former multiple-weight world champion Pacquiao is seeking election to the Senate in May.
A video of Pacquiao was posted on Monday on the Facebook page of Filipino TV channel TV5, titled Mas masahol pa sa hayop – which, translated from Pacquiao's native Tagalog, means "worse than an animal".
According to the BBC, some of Pacquiao's Tagalog comments translate as: "It's common sense. Will you see any animals where male is to male and female is to female? The animals are better. They know how to distinguish male from female. If we approve [of] male on male, female on female, then man is worse than animals."
After this was viewed by more than two million people and condemned by many commentators and media outlets, Pacquiao posted another video just before noon UK time today (Tuesday), with the comment: "I'm sorry for hurting people by comparing homosexuals to animals. Please forgive me for those I've hurt. I still stand on my belief that I'm against same sex marriage because of what the Bible says, but I'm not condemning LGBT. I love you all with the love of the Lord. God Bless you all and I'm praying for you."
Within an hour, the video had been seen more than one million times, and been liked more than 60,000 times – the previous video had attracted 20,000 likes.
In the new video, Pacquiao speaks in Tagalog for the majority before saying in English at the end: "I'm humbling myself before you and before God for my mistake. Thank you and God bless."
In December, the BBC said that Tyson Fury – another boxer who had made several homophobic comments – being named on the shortlist of the Sports Personality of the Year award was "not about endorsing his personal views".