ISLAMABAD, Pakistan--Benazir Bhutto '73 claimed victory early this morning after election returns showed her populist party trouncing the opposition in Pakistan's first open elections in more than a decade.

With 103 of 205 districts reporting, the Bhutto's Pakistan People's Party had 52 seats in the National Assembly compared with 21 for its main rival, the right-wing Islamic Democratic Alliance.

The nine-party alliance includes loyalists of President Mohammad Zia ul-Haq, the military president who died in a plane crash three months ago. Another 30 seats in the assembly went to independents and minor parties.

Bhutto, as leader of the victorious party, would be the first woman to lead this Islamic nation.

Bhutto graduated Cum Laude from the College in 1973.

"The victory the PPP achieved is because of the selfless sacrifices, the struggle by people of the PPP," Bhutto said at a news conference after a rally of 8,000 people on the lawn of her family home in the southern city of Larkana.

The crowd chanted "Long Live Benazir!" and "Benazir, prime minister!"

Former Prime Minister Mohammad Khan Junejo, one of Bhutto's main rivals from the Islamic Alliance, conceded defeat late yesterday in his bid for an assembly seat.

"We're on the losing side," he said of his defeat by a Pakistan People's Party candidate in his hometown of Sindhri. He said the Bhutto party had "succeeded very well."

The chairman of the Alliance, Ghulam Mustafa Jatoi, lost in both districts he contested to Pakistan People's Party candidates.

Under Pakistani rules, candidates may contest more than one seat to improve their chance of election but must forfeit all but one. The vacant seats are contested later in by elections.

The other main rival of Bhutto, chief minister Nawaz Sharif of Punjab state, claimed victory in the race for an assembly seat in Lahore, his hometown, but lost to a Pakistan People's Party member in another district.

Bhutto's father, Prime Minister Zulfikar Ali Bhutto, won the last open election in 1977 by a landslide and prompted a coup by Gen. Zia. Bhutto was convicted of complicity in a murder conspiracy and hanged in 1979.

There were no reports of major violence or fraud while the polls were open.

Within two hours, 7,000 people had assembled in front of the Bhutto villa, chanting "Long live Bhutto!" and "Benazir the prime minister!"

Troops manned sandbagged bunkers and cruised the streets in armored personnel carriers in the southern cities of Hyderabad and Karachi, where nearly 300 people died in ethnic strife in September. Elsewhere, police patrolled streets to keep order.

K.M. Dilshad, spokesman for the Federal Election Commission, said unofficial reports indicated a little more than 50 percent of the nation's 48 million eligible voters cast ballots.

Bhutto voted in her family hometown of Nau Dhero in southern Sind province. "Overall, it's going very well and I feel great," she said.

Former Prime Minister Junejo received election results at his home in Sindhri district. "It's a tough contest, it's a very good contest," he told The Associated Press.