Rail bosses have been told to do more to crack down on graffiti on the UK's network as a way of encouraging more people to start using trains again.
Transport Secretary Grant Shapps said maintaining stations to a high standard helped boost passenger confidence and deter more serious crimes.
He said Network Rail must respond to complaints more quickly and use "all tools and innovations" available.
Network Rail said it was committed to tackling what was a "huge problem".
The firm, which maintains 20,000 miles of track as well as 20 of the UK's largest stations, said it was spending £3.5m a year on ridding the country's rail infrastructure of unauthorised imagery.
It said the pandemic had not caused an increase in graffiti, with cases down about 17% over the past five months.
Ministers are encouraging people to return to offices where it is safe to do so and the number of trains running in England, Wales and Scotland has returned to approximately 90% of pre-lockdown levels.
However, passengers numbers are struggling to recover, after the lockdown caused the biggest drop in daily rail usage for 25 years, with many leading employers telling staff they can continue to work from home.
Mr Shapps said keeping the network clean was an important factor in encouraging passengers to return in greater numbers and the prevalence of graffiti remained a concern.
'Worthy of pride'
He has written to Andrew Haines, the chief executive of Network Rail, to urge the firm to do more to remove markings from station buildings, bridges and other infrastructure.
"I want us as a nation, particularly as we continue our focus on improving and developing our national infrastructure as we recover from Covid-19, to feel proud of our rail infrastructure and public spaces by ensuring that they are maintained to a high standard," he said.
"The blight of graffiti, however, can have an impact on the confidence of passengers as they return to safely using the railway, and on the wider public view of our national infrastructure and public transport."
He said the onus should not be on passengers to have to report cases to ensure graffiti was swiftly removed.
In addition to its annual £3.5m anti-graffiti budget, Network Rail spent £1m on specific projects in April and May.
Mr Shapps said this was a "step in the right direction" but a long-term plan was needed to ensure the railways remained "worthy of pride" and operators used the latest technology to combat vandalism and anti-social acts.
Given the link between illegal trespassing and cases of graffiti, he also urged Network Rail to work with the train operating companies and British Transport Police to "harden the network to unlawful incursions".
Network Rail said it was committed to removing all offensive graffiti within 24 hours of being told about it, identifying offenders and working with youth organisations to warn people of the dangers of trespassing.
Other measures being used include anti-graffiti paints and allowing plants and trees to grow over surfaces that are continually defaced.
It said there has been 324 cases between the start of April and the middle of September, covering the period of the UK-wide lockdown and its aftermath, compared with 389 over the same period last year.
"Graffiti is a huge problem on our network but is not limited to the railway," Mr Haines said.
"We are committed to tackling the problems that graffiti creates by investing money into prevention programmes and looking at ways we can use technology to help us in the battle."
Passenger watchdog Transport Focus said graffiti "costs real money to clean up so any moves to banish it even further are to be welcomed".
"Britain's railways have become fairly graffiti-free in recent years, let's keep it that way," said its chief executive Anthony Smith.