The online hacker organisation Anonymous has sent a warning to a notorious Kansas-based hate group about its plans to protest the funerals of the victims of the Boston Marathon bombings.

Anonymous posted a Tweet on Monday in response to Westboro Baptist Church's declaration of intention to protest the funerals.

"If #WBC protests the Boston funerals, they will have to expect us," posted the "hacktivist" group, whose Tweet received over 3,100 retweets and over 1,700 favourites in less than 48 hours.

Unaffiliated with any Baptist denomination, Westboro announced on the day of the bombing their intention to protest the funerals of the victims that ripped through the Boston Marathon. WBC claimed that the bombings were divine punishment for Massachusetts being the first state to legalise same-sex marriage in the United States back in May 2004.

"THANK GOD FOR THE BOSTON MARATHON BOMBS!! Westboro Baptist Church to picket funerals of those killed. #PraiseGod", reads another tweet from the WBC's Twitter account.

This would not be the first time Anonymous and Westboro have stood against each other. Last December, Anonymous hacked the Westboro Baptist Church website, stealing personal information of WBC members via their server.

In January, when Westboro announced that they would protest the funeral of Reddit co-founder Aaron Swartz, Anonymous stated that they would protect the service from WBC interference.

"We would do anything to stop them from attending Aaron's services," said the hacker group in an online video. "We encourage organisations who would like to form protective human shields near Aaron's funeral to listen closely for any announcement by the family on this action and respect their wishes."

Despite its many declarations of protests for major events, in recent times Westboro's efforts have failed to come to fruition. For example, a promise to protest recently deceased Chicago Sun Times film critic Roger Ebert failed to manifest. While WBC was able to have a presence at their planned protest of President Barack Obama's second inauguration, reports noted that barely a half dozen WBC members were in attendance.

While Anonymous warns WBC of action against them should they demonstrate at the Boston funerals, others have looked toward classifying Westboro as a "hate group" and getting its tax exempt status revoked.

On the White House Petitions website, a petition posted Monday demanding that Westboro be banned from the funerals has garnered over 16,000 signatures.

"We can't let them get into Boston and do this. This is a petition to stop the WBC from getting into Boston, or worse, picketing the funerals of two innocent people," reads the description for the petition.