England internationals Owen Farrell and Mouritz Botha are among 18 players to have agreed contract extensions with Aviva Premiership champions Saracens.

Number eight Ernst Joubert, England Saxons scrum-half Ben Spencer, Sam Stanley and Duncan Taylor have also put pen to paper on new deals.

Saracens will be announcing the rest of the contract extensions over the next two days, although the length of the deals is being kept confidential.

Farrell broke into the Saracens first team last season and, playing fly-half, he guided the club to their first league title with victory over Leicester in the Premiership final.

The 20-year-old made an assured England debut at inside centre in the opening round of the RBS 6 Nations against Scotland.

Farrell's perfect kicking display helped England to a 19-15 victory over Italy and he is set to be named in the side to play Wales this weekend, when interim coach Stuart Lancaster confirms the line-up on Thursday.

Saracens director of rugby Mark McCall said: "Owen obviously has a wonderfully exciting future in the game, at club and international level, and we are delighted he has pledged his future to Saracens."

Botha, who started both England's Six Nations game to date, joined Saracens in 2009 after stints with Bedford Athletic and the Bedford Blues.

Spencer was recruited from Cambridge and, in a rise similar to Farrell's, he was thrust into the first team following an injury crisis at scrum-half. The 19-year-old was fast-tracked into the England Saxons squad for their A international against the Ireland Wolfhounds and he is part of the national Under-20 squad.

McCall said: "Ben has made extraordinary progress this season, from the National One league to the England Saxons, and we are delighted he has extended his contract. Mouritz's progress over the past few years has been fantastic and we genuinely believe the best is yet to come."