The Fire Brigades Union has said that Theresa May was “disgraceful” to mention the Grenfell Tower fire when she announced her resignation date.
The Prime Minister said she had given a “voice to the voiceless, to fight the burning injustices that still scar our society".
She added: "[That] it is why I set up the independent inquiry into the tragedy at Grenfell Tower. To search for the truth so nothing like it can ever happen again, and so the people who lost their lives that night are never forgotten."
The FBU general secretary Matt Wrack said Mrs May mention of the tragedy was “disgraceful”.
“Many of the underlying issues at Grenfell were due to unsafe conditions that had been allowed to fester under Tory governments and a council for which Theresa May bears ultimate responsibility,” he said.
“The inquiry she launched has kicked scrutiny of corporate and government interests into the long-grass, denying families and survivors justice, while allowing business as usual to continue for the wealthy."
Union leaders also offered little sympathy over the Prime Minister's resignation.
Tim Roache, GMB general secretary, said: "This government has given us more farcical scenes than The Thick Of It, and more brutal beheadings than Game Of Thrones.
"No-one is going to be sorry when this series ends.
"Working people are sick of the Tories focusing on who is going to take Theresa May's job when thousands across the country are losing theirs."
Mrs May announced that she would step down as Prime Minister on June 7.