Jimmy Kimmel has joked that Prime Minister Bill English declared war on Italy with his canned spaghetti pizza.

English came under fire for a Facebook post that showed him putting spaghetti on top of a pizza base and cooking it up for his family.

"Cooked dinner for the family last night - like if you agree with tinned spaghetti on pizza!" he wrote on Monday night.

The news quickly went viral, reaching Kimmel's late night show overnight.

And Kimmel wasn't happy, suggesting English might even be worse than America's controversial leader.

"We can be pretty hard on Donald Trump but they have a guy in New Zealand, the Prime Minister of New Zealand, a gentleman named Bill English, who I think is even worse and I'm going to show you why," Kimmel said.

"Not only did he put (tinned spaghetti) on a pizza - he put it on a pineapple pizza. He put canned spaghetti and pineapples on a pizza.

"This mother... That is so offensive. That is an act of war.

"I think he just declared war on Italy ... and maybe Hawaii too."

Kimmel then called for New Zealanders to take control of the situation.

"Impeach that man immediately," he said.

English reportedly told MoreFM his children had forced him to make the pizza post.

"I quite often cook on a Monday night for the household and I had been goaded by my children about how my Facebook needed, every now and again, something a bit more personal," he said.

But a professional pizza chef told The Spinoff his spaghetti concoction didn't even deserve to be called "pizza".

Farina executive chef Sergio Maglione said: "It's more like round toast with stuff on top."

"For me, it's all about using the best and freshest ingredients available - no processed food."

English's pizza goes viral

English's pizza made headlines around the world, including Buzzfeed, who simply said: "This s*** is f***ed up."

In the UK, the Evening Standard ran with the headline: "New Zealand PM Bill English causes storm with 'atrocious' tinned spaghetti and pineapple pizza."

And The Mirror wrote: "A man put something weird on his pizza and people can't decide whether it's a good idea."

The Huffington Post wrote: "New Zealand's Prime Minister Just Concocted A Crime Against Pizza."