According to Scotland Yard, if allegations are proved, the police officers will face court prosecutions and will be also accused of professional misconduct inquiries.
UK law prohibits discriminating against ethnic minorities.
The private Facebook group led Britain's largest police force to put their own members under scrutiny as concerns the racist manner of "endemic" posts are becoming a "part of police culture".
The Met became suspicious about "endemic" posts as late as April when it encountered the "I've Met the Met" group which boasts more than 3,000 serving and retired police officers.
One of the group's members expressed concern over allegedly racist comments like these: "I never knew a pikey could be offended," said one comment. "I thought they were devoid of all normal feelings and thoughts… just my opinion based on many years of dealing with these despicable people."
Another said: "There is not a small minority of criminals from the GT [Gypsy and Traveller] community — to all intents and purposes they all depend on crime."
It appears to be a sore point for the Met which is trying to repair its reputation since 1999 when black teenager Stephen Lawrence was killed in a racist attack by five white teenagers.
The Directorate of Professional Standards (DPS) urged group members to speak out if they believe there are racist comments posted on the group page. It has been passed three months since DPS launched an investigation on the group, said the statement.
"DPS is assessing the information to determine whether any serving MPS officer or staff may have committed any acts of misconduct and will also look to see if any criminal offences may have been committed. Should either be disclosed they will be fully investigated."
The CEO of the Traveller Movement, Yvonne MacNamara, told the Independent magazine that "the fact that they are potentially made by serving and retired police officers gives us no confidence at all in the Metropolitan Police's ability to both police these communities and to attract and protect its own staff who are from Gypsy and Traveller backgrounds."
Jim Davies, chair of the Gypsy Roma Traveller Police Association (GRTPA) added "racism towards Gypsies and Travellers is endemic and is part of police culture," he stressed. "It has been allowed to fester and spread unchallenged for years and the effect on the lives of Gypsies and Travellers in the police service is disastrous."