A Sunday newspaper reported that it will tell the Office of Rail Regulation today 89.9% of trains arrived at their destinations on time.
The benchmark target for Network Rail is 92.5% and ORR fines it for every 0.1% by which it is missed.
Network Rail said excessive congestion and bad weather had offset improvements made to rail infrastructure. A spokeswoman said: "Passengers are not currently experiencing the very high levels of train punctuality we had promised. While we have been successful in making our infrastructure more reliable, it hasn't been enough to offset the difficulties caused by excessive congestion or bouts of extreme weather."