The Foxes strengthened their push to win the premier league for the first time this season with a Wes Morgan goal at the King Power Stadium.
The Dutchman watched as the referee looked away as the ball hit Danny Simpson from a Sadio Mane shot after he had beat goalkeeper Kasper Schmeichel and in the second half Robert Huth escaped punishment when he handled the ball inside the penalty box and no spot kick awarded.
“We started the game badly and lost control, but after 20 minutes we were dominating. But for the third match in a row we don’t get a 100% penalty – Stoke City away, Liverpool at home, and today two penalties,” Koeman told Sky Sports News.
“The big one is when Sadio Mane’s shot hits Danny Simpson and it is a red card and a penalty. If it is not a handball, it is a goal. I don’t know what they are doing. This is a big match. It is about the Premier League title and our ambitions to play in Europe. The second one was when Robert Huth handled.
“I don’t say they don’t deserve the victory,that they don’t fight and have amazing spirit, but if it is a penalty and a red card they don’t win. I don’t think that [the officials] are against Southampton, but it is very strange.”
The win takes Leicester City seven points clear following Tottenham Hotspurs 1-1 draw away to Liverpool while Southampton stay four points adrift of six-placed West Ham United.