Matt Williams was named Ulster coach in December

Ulster are believed to be involved in advanced negotiations with South Africa World Cup winning star BJ Botha, a tighthead prop with Natal Sharks.

The 28-year-old is expected to become the first major signing of Matt Williams' tenure, filling the void left by the recent retirement of Simon Best.

Botha has won 16 caps for South Africa, made 93 appearances for the Sharks and is one of the world's best scrummagers.

Leicester fly-half Ian Humphreys is thought to be another Ulster target.

Humphreys would be a natural replacement for brother David, who retires at the end of the season.

Botha played in all of South Africa's pool games at the World Cup in France, including the 36-0 win over England.

A knee injury sustained in the 64-15 victory over the USA in the final pool match prevented him from playing in the knockout stages as the Springboks went on to be crowned world champions.