(File image) Republican Senator John McCain is on a visit to Mali.

Washington - A leading Republican senator's tweet comparing Iranian President Mahmoud Ahmadinejad to a monkey is drawing criticism from a fellow Republican lawmaker as racist.

On Monday, Senator John McCain wrote: “So Ahmadinejad wants to be first Iranian in space - wasn't he just there last week?” He then linked to a news story about Iran launching a monkey into space.

Faced with criticism, McCain said in another tweet: “Lighten up folks, can't everyone take a joke.”

That did not satisfy Representative Justin Amash, who tweeted: “Maybe you should wisen up and not make racist jokes.”

During the 2008 presidential campaign, McCain, the Republican candidate, created a stir during an appearance when he repeated “Bomb Iran” to the tune of the Beach Boys’ song Barbara Ann. - Sapa-AP