The Office of Fair Trading has launched an investigation into games on phones and tablets that are free to download, but could end up costing parents hundreds - even thousands - of pounds.
It follows concerns that children could be tricked into spending money on upgrades without realising the cost.
More top news
A highly toxic chemical was used in the death of North Korean leader Kim Jong-un's half brother last week, tests have shown.
A new survey has highlighted the disconnect between people's views on the GB Olympic team and funding for grassroots sport.
National Crime Agency officers have arrested a British man in connection with bribery offences linked to international cricket spot-fixing.