Post Office campaigner Sir Alan Bates is yet to receive a reply from Sir Keir Starmer, despite writing to him over a month ago.
Sir Alan said he had written to the prime minister to remind him the "clock is still ticking" on a financial redress deadline for victims.
In his letter, he demanded a March 2025 deadline for compensation for sub-postmaster victims of the Horizon scandal.
Sir Alan confirmed to Sky News he was yet to hear back from the prime minister.
Follow Sky News on WhatsApp
Keep up with all the latest news from the UK and around the world by following Sky News
"It was over a month ago," he said.
"I sent him a reminder yesterday. I told him the clock is still ticking and it's now five months from the March deadline, which I'm told is still achievable by other professionals.
"So let's get on with it, that's all we want. Get on with it."
This breaking news story is being updated and more details will be published shortly.
Please refresh the page for the fullest version.
You can receive breaking news alerts on a smartphone or tablet via the Sky News app. You can also follow @SkyNews on X or subscribe to our YouTube channel to keep up with the latest news.