President Cyril Ramaphosa will not attend this week's Group of Seven (G7) summit in Italy, his spokesperson said on Monday, as his party rushed to find partners to govern the country.

Ramaphosa's African National Congress (ANC) is holding talks with a wide range of other parties, saying it wants to form a national unity government after losing its majority for the first time since the end of apartheid in last month's election.

Diplomatic sources had said Ramaphosa was due to take part in the G7 summit from June 13-15 at the invitation of Italy, which holds the rotating presidency of the G7 and wants to broaden the gathering beyond the usual seven industrial democracies: the United States, Britain, Canada, France, Germany, Italy and Japan.

"The president will not be attending the G7 meeting due to current domestic priorities he needs to focus on," Ramaphosa's spokesperson Vincent Magwenya told Reuters.

Ramaphosa said last week a broad collaboration with other political forces would be the best way to move South Africa forward.

The ANC is under pressure to reach an agreement quickly because the new National Assembly is set to hold its first sitting on Friday.

One of the national legislature's first acts will be to elect the next president, which is still expected to be Ramaphosa as the ANC remains the biggest party.

The ANC will have 159 of the 400 seats in the National Assembly. Its nearest rivals are the pro-business Democratic Alliance with 87 seats, the populist uMkhonto we Sizwe led by former president Jacob Zuma with 58 and the hard-left Economic Freedom Fighters with 39.