Wales's first minister Mark Drakeford has said he was "genuinely baffled" Rishi Sunak did not call him to discuss plans to support people affected by job losses in Port Talbot.
The majority of those will be in the UK's largest steelworks in the South Wales town as the company replaces its blast furnaces with electric arc furnaces.
During first minister's questions on Tuesday, Mr Drakeford told the Senedd he contacted the prime minister's office last Thursday, when it became clear Tata would announce the closure of both blast furnaces in the town.
The first is expected to shut sometime in the middle of 2024 and the other during the second half of the year.
Tata said the move will cut carbon emissions by about 85% and the UK's overall CO2 output by about 1.5%.
It also said its plan will reduce costs, but unions have called for Tata and the UK government to reconsider and warned of a "major industrial dispute".
Tata received £500m of taxpayer cash to support the transition to cheaper, greener steel production.
"I wrote immediately to the prime minister, asking for a telephone call with him on Friday, so that we could jointly discuss how we could best respond to the emerging picture," Mr Drakeford said.
"And by eight o'clock, 8.30, in the morning on Friday I'd had a reply from the prime minister saying that he couldn't find time to meet me or talk to me that day and I do think that is genuinely shocking."
His comments come after the Welsh government's economy minister, Vaughan Gething, told a news conference on Tuesday that the final whistle had "not been blown" on Tata Steel jobs at Port Talbot.
The steel giant has said 2,500 jobs could go in the next 18 months, while a further 300 might be axed in three years' time.
Statutory consultation on the cuts is yet to begin, and a date for that has not been fixed.
The Tata Steel workforce currently accounts for 12% of Port Talbot's entire population.
Nearly three-quarters of the 4,000 staff on site could be out of work following the redundancies.
"On the day that Ford announced that they were leaving Bridgend, my office contacted the office of the prime minister that day and before the end of that day, I was in a conversation with the prime minister about what we could do together to help people who were affected," he said.
"That's what I was looking for from the prime minister and I am genuinely baffled that he did not feel it was a priority for him to find the small amount of time he would have needed that day to have that conversation."
The leader of the Welsh Conservatives, Andrew RT Davies, said he believed there was a "route to keep that blast furnace open".
"I was as surprised as anyone when it came out that they were going to shut both blast furnaces," he added.
In response to Mr Drakeford's comments, Welsh Secretary David TC Davies said he was "disappointed" the first minister had not responded to his own invitation to discuss Tata's announcement.
"To date, the Labour Welsh government has not offered a single penny towards the transition board," he added.
"However, the invitation is there still for the first minister to speak to me to discuss the latest announcement ."