Chelsea have published an article on their official website questioning the "abnormally low" number of penalties awarded to the team in the Premier League this season.
The article, entitled "Penalty puzzle," notes that Chelsea have been awarded only two penalties in their 28 league games so far this season, with the last coming when Eden Hazard won and converted a spot kick in a 2-1 win over Queens Park Rangers on Nov. 1.
The only other penalty, again won and converted by Hazard, came in October's 2-0 win over Arsenal.
Chelsea boss Jose Mourinho has been forthright in his criticism of officials in the Premier League this season, and was fined by the Football Association in January for suggesting his side were the victims of a "campaign."
Since then, he has also spoken at length about the decisions made during last month's 1-1 draw against Burnley, and he complained after Sunday's 1-1 draw with Southampton that two penalty decisions had gone against his side during that game.
Chelsea were awarded a penalty -- as well as seeing Zlatan Ibrahimovic controversially sent off -- during their 2-2 draw with Paris Saint-Germain in the Champions League, but the article suggested such decisions only served to highlight the difference in treatment between domestic and European referees.
The article said: "We were of course the recipient of a spot-kick in our last European encounter, when PSG's Thiago Silva obviously handled in the area, but Champions League referees have spotted penalty incidents throughout, with four also given our way in the group stage.
"It is in our 28 Premier League games this season where we have been awarded just two penalties. Both were for infringements on the league's most-fouled player, Eden Hazard, and both were in home London derbies, against Arsenal and QPR respectively. The most recent was four-and-a-half months ago.
"Historically, this figure seems abnormally low."
A look at penalty numbers from this season and those past... http://t.co/3pm4lc4q6e #CFC pic.twitter.com/iybB343dKt
- Chelsea FC (@ChelseaFC) March 18, 2015
The article features figures for the numbers of penalties awarded in seasons from 2009-10 to 2013-14, ranging from the five awarded when the Blues finished fifth in 2011-12 to the 12 given when Carlo Ancelotti's side won the title in 2009-10.
It continued: "So this season's tally of two unquestionably bucks the recent trend yet our position as clear league leaders and second-highest scorers suggests we can't be labelled anything other than an attacking side, spending plenty of time in the opposition box.
"Our two closest challengers in the Premier League this season, Manchester City and Arsenal, have both been awarded seven penalties -- the most in the division. City have only scored one goal more than Chelsea and Arsenal two less.
"Last term, the two teams that finished above us in the league -- Man City and Liverpool -- were awarded more penalties than any other team bar us.
"Of course, it could be that when teams have played the league leaders they have been particularly careful inside their own area. We all have plenty of recollections suggesting this is not the case however."
The article suggests the issue began "from the first half of our very first league game," when Diego Costa was controversially booked for simulation after appearing to be fouled in the area by Burnley goalkeeper Tom Heaton in an eventual 3-1 win.
Chelsea are currently six points clear at the top of the Premier League with a game in hand, but Mourinho warned after the weekend's match that such decisions ensured they would have to stay on their guard in the title race.
"It is not easy, every match is difficult, and in our two matches against Southampton, in one there was penalty that is not a penalty and in another game a penalty that was not given, so you are speaking about six points becoming two points, so the danger is always here," he said. "But I keep saying: we are there."