NEW DELHI - Indian Prime Minister Narendra Modi and visiting US President Barack Obama said on Sunday that the two countries have reached an agreement to break a six-year impasse on the landmark civil nuclear deal.

"The civil nuclear deal was the centerpiece of Indo-US understanding. Six years after we signed a bilateral agreement we are moving towards commercial viability," Modi said at a joint press conference with Obama.

"In the past four months, we have got a sense of purpose to move it forward. The success of this partnership is crucial to advancing peace and prosperity," he added.

Though Modi did not clearly say whether the nuclear deal has been finally inked, President Obama was more categorical after the differences were ironed out. "We have achieved a breakthrough understanding on the civil nuclear deal," he said.