LIMA, June 15 (Reuters) - Peruvian socialist candidate Pedro Castillo claimed victory in the presidential election on Tuesday after clinging on to a narrow lead as the lengthy vote count ended, although his right-wing rival pledged to fight the result and has yet to concede. Castillo ended the count 44,058 votes ahead of Keiko Fujimori, who has made allegations of fraud with little proof and has tried to get some votes annulled. The result of the June 6 ballot has not been formally announced by electoral authorities, but Castillo hailed the win on Twitter. "A new time has begun," Castillo wrote, alongside a picture of himself with arms raised, the word "President" in large font and his campaign slogan: "No more poor in a rich country." He also updated his Twitter profile to include "President-elect of the Republic of Peru (2021-2026)." The abrupt rise of the 51-year-old former teacher has rattled Peru"s political and business elite and could have a major impact on the vital mining industry in the world"s No.2 copper producer, with Castillo planning sharp tax hikes on the sector. Fujimori, addressing supporters at a rally in downtown Lima on Tuesday, pledged to keep fighting and "defend Peru"s democracy". She hoped the result would swing her way once ballots that her party is seeking to annul had been checked. "Today a result has come out, yes, a result from the ONPE (electoral body) count, but the most important thing is the evaluation of the ballot boxes," she said. "We trust the authorities yes, but we trust more in the popular will." Castillo"s Free Peru party has rejected accusations of fraud and international observers in Lima have stated that the elections were transparent. WILL OF THE PEOPLE Castillo had vowed earlier in the day he would not allow rivals to deny the will of the people and overturn the election, which has seen supporters on both sides take to the streets in recent days. The son of peasant farmers, Castillo had 50.125% of the votes while Fujimori, the eldest daughter of imprisoned former president Alberto Fujimori, had 49.875%. Castillo told reporters at the Lima headquarters of his party that he would respect electoral authorities and urged them to end the uncertainty by confirming the result quickly. "We"re not going to allow an oppressed people to continue to be discriminated against for more years," Castillo said. "Things have been put on the table democratically, and there needs to be a democratic way out." Election observers said it could take days or even weeks for the authorities to deliberate the legal challenges and to declare a winner. Peruvians who had cast their votes for Castillo have grown impatient. Ricarte Vasquez, 32, originally from northern Cajamarca, called the deadlock "shameful" as he was selling a breakfast snack of fried sweet potato and yuca on a busy Lima junction where mini buses pick up passengers. "If Keiko had won, it"d already be decided," Vasquez said. "I voted not only for a change in the government but also for a change in the country." Vasquez said he hoped the situation for informal workers like himself, many of whom were hit hard during a months-long lockdown to curb the spread of the coronavirus, would change with Castillo as president. Luz Maria Quispe, 37, originally from Cusco, said she had also voted for Castillo and did not believe fraud claims. "We want this change for Peru," she said, standing in front of a statue of the Virgin Mary in a Lima park where she and the elderly person she was caring for had stopped to pray. "What I"m asking Senora Keiko Fujimori is that she now accepts defeat: the people have decided." Quispe said she had studied to become a nurse but was forced to quit because she could no longer afford tuition. Socialist Castillo has galvanized rural and poorer voters who feel left behind in the country"s economic growth. His rise could portend a swing to the left in Brazil, Chile and Colombia, who will vote for new leaders this year and next. Reporting by Marco Aquino; Writing by Adam Jourdan