The event - now in its 10th year - gives pupils a taste of working in the media, meeting deadlines and writing for a real audience.
Pupils can research news on the Internet or receive it by fax or e-mail from organisers. They use resources on the TES Newsday website including features on subjects ranging from Formula One racing to the general election.
Schools involved come from Eurpe, Sri Lanka, the Falkland Islands, Kuwait and Chile.
St Paul's School for Girls in Hammersmith, west London, is taking part for the third year after winning accolades in 1999 and 2000.
School magazine editor Liz Lindesay said: "We wanted a chance to show off all the areas that we cover in the school magazine and produce a newspaper too.
"We have a very strong team already which has helped a lot."
The winners will be announced at a ceremony in London in June.
The Newsday website is at www.newsday.co.uk