Tea maker PG Tips is to switch to fully biodegradable, plant-based teabags, parent company Unilever has announced.

Most manufacturers currently use polypropylene to seal teabags – they say it strengthens them and stops them disintegrating in a cup.

Unilever said the move to plant-based sealants was based on “cutting edge science and technology”.

The first eco-friendly pyramid teabags go on sale next week – other teabag types will follow later this year.