RELATIVES of some of the victims of the Lockerbie bombing are said to be horrified at the intrusion on their grief as US attorney general William Barr unsealed charges against another possible suspect on the anniversary of the atrocity.

Barr said the US had charged a "third conspirator" in connection with the bombing, telling a news conference Abu Agila Mohammad Masud Kheir Al-Marimi was identified along with two Libyan intelligence agents during the investigation in 1991.

At the time, he said investigators could not "identify or locate" this person.

"The United States has filed criminal charges against the third conspirator, Abu Agila Mohammad Masud Kheir Al-Marimi, for his role in the bombing of Pan Am flight 103," he added.

Scots lawyer Aamer Anwar, who represents some of the families, said the fact that Barr thought it “appropriate” to invite the families to watch his “grandstanding” this afternoon is “deeply disrespectful to the families and victims”.

He was speaking from Lockerbie with two of the families 32 years to the day that Pan Am flight 103 exploded over the town.

READ MORE: US set to announce new charges over Lockerbie bombing

Rev John Mosey, who lost his 19-year-old daughter Helga, wrote to the Crown Office and the attorney general to express his disgust at the invitation.

“We consider the timing and particularly the choice of this specific day, which is special to many of us, to be bizarre, disrespectful, insensitive and extremely ill considered,” he said.

“Why exactly when the attorney general is about to leave office, has he waited 32 years to bring charges?

“Why would you use the anniversary of our daughter Helga’s death along with 269 others to parade once more a highly suspect prosecution?

“Your own department, and perhaps some parts of the Scottish legal system, should also be investigated for spending over three decades trying to divert the course of justice and hide the truth.”

The National: Abdelbaset al-MegrahiAbdelbaset al-Megrahi

Ali Megrahi, whose late father Abdelbaset was the only person convicted of the bombing, but whose conviction is subject to a third appeal, said: “Monday is just another desperate excuse to accuse Libya and after 32 years want to accuse another Libyan. Why now?

“Where were they in the past 32 years, especially when we have been fighting for an appeal over the last six years, so why release this information now?

“They want to perpetuate lies against Libya and will not let us live in peace – I lost my father and yet America continues to cause our family as well as those of the victims more pain.

“As for the American families of the victims of this atrocity, you lost loved ones and I lost my father, I am not against what you are doing, but I assure you that your government have lied to you for the past 32 years and my family and I will not give up fighting for truth and justice.”