Retailers' hopes of blocking a ban on cigarette displays suffered a blow this week as new figures revealed the number of shops caught selling cigarettes to underage smokers has increased by nearly 50%.

Of 457 retailers across England tested by trading standards officers, 19% were caught selling tobacco to under-18s. This compared to a guilty 13% of the 241 who were tested the previous year, according to the local authority body Lacors.

The worst offenders were independent newsagents, 23% of which were caught making illegal sales.

"This worrying increase shows that retailers are not doing enough to make sure they aren't selling cigarettes to kids," said Lacors chairman Geoffrey Theobald. "This isn't rocket science and it isn't anything new for retailers. If they suspect someone is underage who can't prove otherwise then they must refuse to serve them or face the consequences."

The poor performance by independents was branded unacceptable by the chief executive of the Association of Convenience Stores, James Lowman.

"These figures are a reminder for all retailers to be extremely diligent and vigilant when it comes to tobacco sales," he said.

The figures will undoubtably be picked up by the health lobby as the argument over the proposed ban on displaying tobacco intensifies.

Labour MP Jim Dowd has tabled an early day motion calling on the government to consult with the industry about the effect the ban would have on small shops. Last month the ACS predicted a ban would cost the independent sector £252m.

But the proposed ban has been welcomed in some quarters.

"If we want to continue to bring down smoking rates we need tough action to make sure children cannot get their hands on tobacco products," said David Rogers, chair of the Local Government Association Community Wellbeing Board.