Lithuania's President Gitanas Nausėda and Latvia's Egils Levits also took part in the high-profile opening ceremony in Jauniūnai near the Lithuanian capital Vilnius, alongside the European Union's Commissioner for Energy Kadri Simson and Baltic energy ministers, public broadcaster Polish Radio’s IAR news agency reported.
Duda said during the event that "the interconnector between the natural gas transmission systems of Poland and Lithuania" as well as those of the two other Baltic states, Latvia and Estonia, was a response to "another blackmail attempt" by Russia involving gas supplies.
"Thanks to projects such as this, we provide ourselves with an alternative, the possibility of deliveries from markets other than Russia," he added.
"I am glad that this interconnector will serve us and to a large extent ensure diversification for other European Union countries," Duda also said.
The 508-kilometre GIPL pipeline will ultimately have the capacity to carry 2 billion cubic metres of natural gas annually from Lithuania to Poland and 2.5 billion cubic metres the other way, Polish state news agency PAP reported.
A Swiss magazine reported last month that Poland was building new pipelines to Lithuania, Slovakia and Germany to source gas from these neighbouring countries as an emergency option and to send gas there from its purchases elsewhere.
Russia’s energy giant Gazprom last week suspended gas deliveries to Poland and Bulgaria after the two countries refused to pay in Russian roubles amid Moscow's invasion of Ukraine, according to officials.
European Commission chief Ursula von der Leyen said last month that Gazprom's decision to stop delivering gas to European customers was "yet another attempt by Russia to use gas as an instrument of blackmail."
Polish Prime Minister Mateusz Morawiecki told reporters that his country had sufficient reserves and alternative supply routes after Russia said it was suspending gas supplies to Poland under a long-term contract.
Poland uses about 20 billion cubic metres of natural gas a year, experts say.
Source: IAR, PAP
Click on the audio player above for a report by Radio Poland's Michał Owczarek.