Alec Baldwin has explained his decision to appear in a scene featuring a horse-drawn carriage, revealing he only agreed to it if his 30 Rock character could deride the unpopular New York tourist practice.

The star has been a longtime opponent of the carriage rides around Central Park, agreeing with other animal lovers that it's cruel to ask horses to trudge around the city.

And so, after filming a scene for Tv comedy 30 Rock in which his character Jack Donaghy appears with a carriage, Baldwin felt it necessary to open up about his reasons.

In an email to friends at People for the Ethical Treatment of Animals, he writes, "Rolling torture wagons for nature's most dignified creature: That's how my 30 Rock character describes horse-drawn carriages, and it's why I agreed to appear in a scene featuring a carriage.

"It reflects my personal belief that New York should join Toronto, London, and Paris in outlawing hansom cabs from city centers. I've been speaking out with Peta against the cruelty of horse-drawn carriages for decades, and I'm thrilled that Intro 86A, the bill to replace the carriages with eco-friendly classic-replica cars, has garnered so much support in City Council."