"We want to free Corporal Gilad Shalit, but we want Israel to free a certain number of our prisoners - we will specify how many," Khaled Mashaal told a news conference in Moscow.
Shalit is a 19-year-old corporal taken hostage by Palestinian gunmen in June 2006. They have insisted that they would not release the captive until Israel freed all Palestinian women and children from its jails.
Mashaal also said Israel must end the occupation of Palestinian territories before Hamas makes a final decision on the recognition or non-recognition of the state of Israel.
"When it does [pull out], the Palestinian people will clearly present their position," he said.
He also said Hamas representatives will visit Iran soon.
"Hamas has good relations with Iran, and we will soon visit Tehran," Mashaal said, adding that Russia may provide humanitarian aid to the Palestinian National Authority.
He said the Russian leadership is also working to ensure that Palestinian financial assets be unfrozen.
"These assets have been frozen in U.S. bank accounts," he said.
Russia will support the Palestinians and push for an international economic blockade of the Palestinian National Authority to be lifted, Foreign Minister Sergei Lavrov said at a meeting with Hamas' political leader earlier Tuesday.
Palestinian Islamist group Hamas is visiting Moscow against the backdrop of a deadlock in peace talks with Israel and bloody inter-factional clashes in Palestinian lands, and in the wake of a series of international meetings on the Middle East conflict.
"The participants at the Mecca meeting displayed wisdom, prudence and - most importantly - responsibility towards the Palestinian people, and we actively support this movement and are trying to ensure that the whole international community back this process, and assists [the PNA] in lifting the blockade on Palestinian territories," Lavrov said.
Lavrov said Russia backed the idea of establishing a national unity government for the PNA from the very beginning, in May 2006, and that Russia has consistently supported specific steps and measures to promote the process.
Hamas and the President Mahmoud Abbas-led Fatah movement agreed to form a power-sharing Cabinet in Mecca two weeks ago, ending weeks of bloody street clashes between their supporters.
Lavrov said a deal reached between Fatah and Hamas in Mecca paves the way for the resumption of talks on the Middle East peace process.
Mashaal said the most important achievement of the Mecca talks was that Arab and Muslim countries shared responsibility for the resolution of the Palestinian problem.
"I believe it is very important that the Mecca agreements reflect the responsibility of Muslim and Arab countries in the resolution of the Palestinian problem," he said.