* Most results in, more of Hezbollah's oldest allies lose seats
* Saudi-aligned Lebanese Forces gains ground
* Parliament more fragmented, deadlock could derail reforms (Adds details on election, likely makeup of parliament, context on reforms, political appointments)
By Laila Bassam, Timour Azhari, Maya Gebeily and Tom Perry
BEIRUT, May 16 (Reuters) - Iran-backed Hezbollah and its allies are likely to lose their majority in Lebanon's parliament, three sources allied to the group said on Monday, in a major blow to the heavily armed faction that reflected widespread anger at ruling parties.
Sunday's election - the first since Lebanon's financial collapse and the Beirut port blast of 2020 - also produced wins for the Saudi-aligned Lebanese Forces (LF), a Christian party, and reform-minded candidates across sects.
Their breakthroughs, however, could fracture parliament into several camps and polarise it more sharply between Hezbollah's allies and opponents. Those opponents are not currently united into a single bloc.
The deadlock could derail reforms required to unlock support from the International Monetary Fund to ease Lebanon's economic crisis and delay parliamentary decisions on a speaker, a premier to form a Cabinet, and a new president later this year.
Preliminary results indicate a reversal of Lebanon's last election in 2018, when Hezbollah and its allies won 71 of parliament's 128 seats, pulling Lebanon deeper into the orbit of Shi'ite-led Iran and away from Sunni-led Saudi Arabia.
Sunday's result could open the door for Riyadh to exercise greater sway in Beirut, long an arena of its rivalry with Tehran.
There was no immediate comment from Saudi Arabia, but Iran on Monday said it respected the vote and had never intervened in Lebanon's internal affairs.
The United States, which has imposed sanctions on Hezbollah, welcomed the elections and encouraged politicians to recommit to economic reforms.
'NATIONAL CELEBRATION'
The interior ministry has announced results for 12 of the 15 districts, but several parties said they would be submitting appeals.
Political sources allied to Hezbollah had earlier said their preliminary counts showed it was improbable the party and its allies would secure more than 64 seats.
Among the notable losses is top Hezbollah ally and deputy parliament speaker Elie Ferzli, 72, who lost the Christian Orthodox seat in West Beqaa, according to official results.
Ferzli lost to a candidate backed by established Druze leader Walid Jumblatt, but Jumblatt's list also lost a Sunni seat to independent candidate Yassin Yassin.