The finding disproves the idea that regular tea drinking can dehydrate the body because of its caffeine content.

The research also found no negative health effects from drinking that amount of tea.

In the clinical trial, 21 volunteers drank either four 240ml mugs of tea over a 12-hour period, equivalent to just under one litre of tea in total or a similar amount of plain, boiled water served warm.

The tea included 20ml of semi-skimmed milk but no sugar.

The test was also repeated using six cups of tea or plain water, equivalent to nearly 1.5 litres of fluid, to investigate the effect of intakes.

Blood samples were taken before consumption and at regular intervals to check hydration levels.

"Tea is an excellent way to maintain healthy fluid levels. In addition, tea is a rich source of flavonoids, which have been associated with a reduced risk of heart disease and stroke," studied by British journal of nutrition.