"The suco elections, our community leaders elections, held across the country last Friday show that the (ruling coalition) parties' votes have crashed," Fretilin lawmaker Arsenio Bano said in a statement.
Fretilin says 66 percent of the newly elected local councils are aligned with the party or its allies, despite village-level candidates being barred from running as representatives of political parties.
Official results from the vote do not record candidates' party affiliations, so it is impossible to verify the opposition's figures.
The claims cap off a tense week in East Timorese politics after Fretilin pushed a no-confidence motion against the government in parliament over the release from custody of an indicted Indonesian former militia leader.
The coalition led by Prime Minister Xanana Gusmao survived the attack, but the debate was rowdy and government spokesman Agio Pereira slammed Fretilin for attempting to "create instability".
Fretilin Secretary-General Mari Alkatiri said the village election results were reason enough for the government to call early elections, amid concerns about stability in the tiny half-island nation.
UN Secretary-General Ban Ki-moon warned Monday that underlying community-level tensions remain in East Timor seven years after it gained formal independence from Indonesia, leaving the door open for conflict.
"More time is required to ensure that the various efforts aimed at tackling the many political, institutional and socio-economic challenges facing the young nation ... are allowed to take root in democratic institutions and processes," he said in a report on the UN mission in East Timor.
President Jose Ramos-Horta has cited the peaceful village elections as a sign of stability and "political maturity".