Ryanair's passenger numbers for April rose by 6% as it operated over 103,000 flights during the month.

Overall, the budget airline carried a total of 18.3 million passengers last month, up from 17.3 million in the same month last year.

The airline said its load factor for April, which is how many seats it fills on each flight, rose to 93% from 92% in April last year.

The strong passenger numbers come after reports the airline has threatened to cancel orders for hundreds of Boeing aircraft if prices are made materially higher by US tariffs.

The Irish airline, which is one of the US aerospace giant's biggest customers, said it could look at alternative suppliers such as China's COMAC, according to Reuters.

In a letter to a US congressman, Ryanair CEO Michael O'Leary said tariffs announced by US President Donald Trump could threaten orders for 330 Boeing 737 Max aircraft that cost $30bn.

"If the US government proceeds with its ill-judged plan to impose tariffs, and if these tariffs materially affect the price of Boeing aircraft exports to Europe, then we would certainly reassess both our current Boeing orders, and the possibility of placing those orders elsewhere," O'Leary said in the letter.

The letter was a response to a warning by Raja Krishnamoorthi, a Democratic representative from Illinois, about the security implications of Ryanair following through on an earlier suggestion it might consider a COMAC order.