Pope Francis will visit the Baltic states next year when Estonia, Latvia and Lithuania mark the centenary of their independence from Russia.

"In principle, we have the decision, we've heard it. Officially it will be announced in December," Lithuanian President Dalia Grybauskaite told reporters in the country's capital Vilnius.

"The occasion is beautiful because the Baltic states will celebrate the centenary," she said, adding that the visit will take place in autumn 2018.

It will be Pope Francis' first visit to the Baltic nations since his election over four years ago.

"It will be a huge gift for Lithuania, and, I hope, also our neighbours," Grybauskaite added.

Catholics constitute about 78% of Lithuania's three million inhabitants, compared to about 20% in Latvia and less than 1% in Estonia. 

Spokespeople for the Latvian President Raimonds Vejonis and his Estonian counterpart Kersti Kaljulaid echoed the sentiments of their Lithuanian counterpart.

A spokesman for Kaljulaid told the Baltic News Service the papal visit to the Baltic states will likely take place from 16 to 18 September next year.

The Vatican never confirms papal itineraries abroad until a few months before they are to take place.  

In February, Lithuania will mark the cenenary of its declaration of independence from Russia following over a century of imperial rule by Moscow.

The largely Lutheran Latvia and largely secular Estonia followed by declaring independence later in 1918.

But initially, the trio's independence lasted only 32 years.

In the first year of the Second World War, the Soviet Union annexed them under a deal with Nazi Germany.

However, the three broke free from the crumbling Soviet Union in 1990 and 1991 before joining the EU and NATO in 2004.

The late Polish-born Pope John Paul II visited all three Baltic states in 1993.