Image copyright Getty Images/Mark Wilson Image caption Mitch McConnell's bill will raise the national minimum age for tobacco purchases to 21

US Senate majority leader Mitch McConnell has announced a bill to raise the minimum age for buying tobacco products from 18 to 21 nationwide.

At a news conference on Thursday in Louisville, Kentucky, the Republican said the legislation would cover products including vaping devices.

Eleven states have already enacted similar legislation, raising the age required to purchase tobacco to 21.

Mr McConnell's proposed law will mirror those state laws already in place.

It will "protect the health of teens nationwide," he said.

"For some time, I've been hearing from the parents who are seeing an unprecedented spike in vaping among their teenage children", Mr McConnell said, adding that smoking was "reaching epidemic levels" in young people.

He said his bill, which will be introduced in May, will be similar to current legislation used to enforce the minimum age of 18. The bill will have exemptions for those who serve in the military.

Louisville, the place of Mr McConnell's announcement, is home to some of the highest cancer rates across the US, with 34% of cancers in the state linked directly with smoking.

According to Mr McConnell, 45% of Kentucky high school students report having tried vaping, mirroring a national rise in the popularity of e-cigarettes.

The Centres for Disease Control and Prevention (CDC) estimates that about 1 in 5 high school students - or 20.8% - reported using e-cigarettes in 2018, an increase from 1.5% in 2011.

Image copyright Getty Images Image caption E-cigarette use is on the rise among US teenagers

Opinions are somewhat divided on the use of e-cigarettes, which are said to be less addictive than cigarettes. Traditional cigarette use, the CDC says, has fallen from 2011 to 2018.

The announcement comes just a day after Mr McConnell announced his bid for re-election in 2020.

The video kicking off his campaign highlights the passage of a farm bill that included a provision that legalises hemp, intended to boost the economy in Kentucky and other farm states as tobacco sales decline.