CNN mistakenly reported that the California Supreme Court had upheld the state's ban on gay marriage on Thursday.

Anchor Don Lemon discussed the result with a legal analyst for about five minutes before realising he had misread the newswire report on the case.

The ruling was keenly awaited in the US and CNN wanted to begin coverage as early as possible.

Bridget Leininger, a spokeswoman for the news broadcaster, said: "It was a misspeak. It doesn't happen often but once in a while it does on live TV.

"(Lemon) was reading the decision and he misspoke, it was not intentional. You trip over one word and it just all goes off from there."

The court in fact found that state law banning marriage of same-sex couples was unconstitutional.