Merseyrail responded to a customer's complaint about a lack of social distancing on an overcrowded train.
On Saturday, a user tweeted the company saying the train she was on was nearly full due to having only three carriages.
She said the lack of space made social distancing an issue.
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Christine Shearer said: "@Merseytravel. Three car carriages on Saturday? Really? Only been on three stops & the train is nearly full.
"How can we be expected to social distance? Not even one metre never mind two. Shocking, don't know who made this decision but it's disgraceful. #safetravelNOT."
However, Merseyrail responded explaining the reason behind the carriage numbers.
Merseyrail said: "Hi Christine, thank you for your feedback, I'm sorry for any discomfort caused.
"While we do continue to monitor all of our services, we are not able to provide six carriages at all times due to the amount of trains we have available.
"We also understand that it won't always be possible to fully social distance while onboard so along with the government guidance, all passengers (unless exempt) must wear a face covering throughout their journey."
Merseyrail's travel advice