He said this at a joint briefing with Ukrainian President Petro Poroshenko in Kharkiv on Wednesday, an Ukrinform correspondent reports.
"We also talked [with Petro Poroshenko] about support for Ukraine through investments in the construction of gas interconnectors. I am glad that this investment task is being implemented and that there is close cooperation between Poland and Ukraine. We are open to the question of possible proposals from Ukraine regarding the supply of liquefied gas," Duda said.
"On the one hand, we want to be a security provider, and, on the other hand, we also feel that building an interconnector strengthens our security and increases our trading and business opportunities. This is the essence of investments," he added.
Poroshenko, in turn, said that Nord Stream 2 was a political project that threatens the energy security of the whole of Europe.
"We are very grateful to Poland for a common position with regard to Nord Stream 2 - it poses a threat not only to the energy security of Ukraine or Poland, but also a threat to the energy security of the whole of Europe," Poroshenko said.
At the same time, he expressed hope that the "joint voice" of Ukraine and Poland in this matter, along with partners from the EU and the U.S., would be "sufficiently effective" in further steps on energy security.
The final date for commissioning a gas interconnector between Ukraine and Poland is 2022, but Poland hopes that it will start operating in 2020.
According to Pawel Stanczak, head of PJSC Ukrtransgaz, the interconnector with Poland will enable Ukraine to become a gas hub.
He recalled that a new gas interconnector between Ukraine and Poland would help increase gas transportation between the two countries to at least five billion cubic meters.