Time is running short as Greece may not have enough money to repay earlier loans from the IMF that are due in a series of payments from June 5.
Tsipras on Wednesday said Greece was "close to an agreement" and his Economy Minister Yiorgos Stathakis said negotiations would conclude by Saturday.
Greece's creditors, on the other hand, insist that insufficient progress has been made in the talks to warrant such optimism.
German Finance Minister Wolfgang Schaeuble late on Wednesday expressed surprise, noting that "little progress" had been made in the talks.
"I am always surprised when we are told by Athens that an agreement is imminent," he told German station ARD.