Russian President Vladimir Putin said Wednesday that he and Ukrainian President Petro Poroshenko could reach a ceasefire agreement as early as this week, even though both sides continued to fight.

Putin said he and Poroshenko are "very close" to an agreement, but Western leaders fear that Putin is saying this ahead of a NATO meeting in Wales Thursday to discuss imposing new sanctions on Russia for its involvement in the conflict, Reuters reported.

U.S. President Barack Obama said the only way a ceasefire would work is if Russia stopped sending troops into Ukraine to support pro-Russian rebels in the eastern part of the country.

Ukrainian forces on Wednesday renewed attacks on the rebel redoubt of Donetsk, increasing concerns that peace may be difficult to obtain. Still, Poroshenko's office said some agreements are in place.

"The parties reached mutual understanding on the steps that will facilitate the establishment of peace," Poroshenko's office said in a statement. The president's office had previously mentioned the possibility of a permanent ceasefire, but that was refuted.

Dmitry Peskov, Kremlin spokesman, said the Putin and Poroshenko had agreed on steps toward peace but had not agreed a ceasefire because Russia was not a part of the conflict, which has killed more than 2,600 people since April.

Putin said he has outlined seven steps that could help bring peace between the two sides, including a prisoner exchange, the creation of a humanitarian corridor for refugees and aid, a Ukrainian pullback, and a halt on the rebel offensive, USA Today reported.

The West has accused Russia of supplying the rebels with arms since the conflict started in April, and more recently accused it of sending troops to join the fracas. Western sanctions came as a result of these allegations, which Russia continues to deny.

"We have consistently supported the effort of President Poroshenko of achieving a meaningful ceasefire that could lead to a political settlement," Obama said.

"So far it hasn't helped, either because Russia has not been serious about it or it's pretended that it's not controlling the separatists, and separatists, when they thought it was to their advantage, have not abided by the ceasefire."