United States president Donald Trump warned countries against opposing his nation's joint 2026 World Cup bid.

USA, Canada and Mexico have put together a joint bid for the showpiece tournament in eight years' time.

Morocco are the rival bid, with the decision set to be announced by FIFA in Moscow on June 13.

In a tweet on Thursday, Trump warned nations not to lobby against the USA, which hosted the event in 1994.

"The U.S. has put together a STRONG bid w/ Canada & Mexico for the 2026 World Cup," he wrote.

"It would be a shame if countries that we always support were to lobby against the U.S. bid.

"Why should we be supporting these countries when they don't support us (including at the United Nations)?"