The show runs until Thursday

The annual event, which runs for four days, is expected to attract 200,000 visitors to the showground at Llanelwedd, Builth Wells.

Up to 7,000 livestock entries will compete for prizes at the show, and more than 1,000 trade stands will offer a range of goods, including Welsh food produce, handicrafts, jewellery and antiques.

In 2001, the show had to be cancelled because of the foot-and-mouth crisis, and organisers suffered losses of �500,000.

But the show recovered in 2002 to record a profit of �250,000.

The show, which was officially opened at 1030 BST in the bandstand, has controversially banned dogs on the showground this year.

Organisers said the dog ban - with the exception of guide dogs - was made on health and safety grounds as unleashed pets had caused "chaos" in animal sheds in the past.

Several politicians are due at the show, including First Minister Rhodri Morgan and Welsh Secretary Peter Hain.

The show attracts thousands of visitors from across Wales

Mr Hain will visit on Monday, and is scheduled to meet representatives from the National Farmers' Union (NFU) and the Farmers' Union of Wales (FUW).

Franz Fischler, the European Union commissioner for agriculture, will attend the show on Thursday, and will be questioned by young farmers.

During the show, the Welsh Conservatives have started a petition against the Hunting Bill, arguing a ban on hunting would have an adverse effect on rural Wales.

As part of the show programme itself, people from around Wales will be giving a demonstration of hunting techniques every afternoon in the main circle.

Arts plans

Plans for a new arts and education centre at the showground are also on display all week. It is hoped they will be built to mark the show's centenary in 2004.

The buildings are designed to become a focal point for arts, culture and youth activities in mid Wales and will include conference, seminar and meeting facilities.

They will also house new offices for the society and provide improved facilities for members, judges and stewards.

Major show awards, including the Royal Welsh scholarships and student of the year awards, will be presented on Monday afternoon.

In an attempt to ease traffic build-up, Wales & Borders Trains is putting on a special service calling at stations across south Wales, including Cardiff Central, Bridgend and Ammanford.