Singh, who has raised a banner of revolt against Haryana Chief Minister Bhupinder Singh Hooda, had recently met BJP President Amit Shah and there were indications that he may join BJP.
Singh had earlier served as an AICC General Secretary and is a Rajya Sabha MP. He was made a member of CWC, the party's apex decision-making body during the last AICC reshuffle.
In a letter to Singh, AICC General Secretary in-charge of party affairs in Haryana Shakeel Ahmed is learnt to have drawn his attention towards media reports of his meetings with BJP leaders including Shah.
The party is learnt to have pointed out that there are media reports that he is hobnobbing with BJP leaders without any contradiction or denial from his side. The party has also taken note of his meeting with Shah two days back and his subsenquent statement that he discussed political issues.
"All these actions are detrimental to the party's interests and have given the party a very bad name. As you are a party MP, you are requested to explain your position within three days," the party is learnt to have told him.
The letter also notes that if the party does not receive a reply from him, it would be construed that he has nothing to say.
Singh earlier said he would attend a rally at Kaithal on August 18, to which Shah too has been invited.
Asked if he would join BJP at the rally, Singh, a known detractor of Hooda, said "there I will make a formal announcement regarding my next step".
Asked if this means he would join BJP, he said, "that is your interpretation" and declined to make any further comment on this issue. He said the Kaithal rally is being organized by Hisar-based social organization Yuva Shakti.