The European Central Bank (ECB) has today unveiled the new €20 note which is set to go into circulation in November.

The new design will include improved security features and will be the first euro note to incorporate a so-called portrait window, which becomes transparent to reveal a depiction of the mythological figure Europa when held against the light.

"The portrait window is a real innovation in banknote technology. It is the outcome of the Eurosystem's work to ensure that the euro notes continue to be resilient against counterfeiting," said ECB president Mario Draghi, speaking at a launch ceremony in Frankfurt.

“This will reinforce the trust that the 338 million citizens across the euro area place in their banknotes,” he added.

It is the latest in the series of new generation Europa notes issued over recent years, following the introduction of a new €5 in 2013 and a new €10 last year.

The €20 note is one of the most widely-used denominations across the continent, according to the ECB, and euro banknotes available across the 19 EU countries are worth a combined total of €1,000 billion.

The rollout of updated currency is expected to continue for several years, with the €50, €100, €200 and €500 from the original 2002 mint still to be replaced.