BEIJING - At least 119 people were killed in a fire at a poultry processing plant in northeastern China on Monday, local officials said, in what appeared to be the country’s worst blaze for 12 years.

More than 300 workers were at the Baoyuan poultry plant at Dehui in Jilin province when the fire broke out and emergency workers searching for survivors were uncertain how many remained trapped inside, Xinhua news agency said. “As of 4:25 pm, altogether 119 people died,” the Jilin provincial government information office said on Sina Weibo, a service akin to Twitter.

The latest post did not say how many were injured, but the local government earlier put the number at at least 54.

It is the country’s worst fire for more than a decade, according to listings on internet portal Baidu. On December 25, 2000, a blaze at a shopping centre in Luoyang, in the central province of Henan, killed 309 people.The slaughterhouse gate was locked when the fire broke out but about 100 workers escaped, Xinhua added. The facility had a “complicated interior structure” and narrow exits which were slowing the rescue work, it said.

The cause of the blaze, which highlights lax safety standards at many Chinese workplaces, was not immediately clear, but state broadcaster CCTV said eyewitnesses had heard a blast and suspected a chemical leak. CCTV also said on its Weibo account that the blaze might have started with an electric spark in the plant.

China’s state-broadcaster CCTV showed the plant surrounded by red fire engines, with its roof apparently burnt away to reveal charred black girders.

 A dramatic photo taken earlier and posted on a Hong Kong-based online news portal showed dense clouds of black smoke several times higher than the low-rise plant. A bright blaze could be seen inside a row of windows in one part of the processing plant. The image could not be independently verified, although the building looked similar to the one shown by CCTV.

Photos from Xinhua showed charred walls and rooftops at the plant, with a row of fire engines standing by.

The Jilin Baoyuanfeng Poultry Company, which began operations in 2009, employs 1,200 people and produces 67,000 tonnes of chicken products per year, Xinhua said. China News Service said that as of the end of 2010 it had sales of 230 million yuan ($38 million).

Meanwhile, China News Service said that as of the end of 2010 it had sales of 230 million yuan ($38 million).

Workplace safety standards can be poor in China, where fatal accidents happen regularly at mines and factories, with some blaming lax enforcement of rules.

But loss of life is rarely on such a scale as the Jilin fire. A major blaze at a Shanghai apartment building in 2010 left 58 people dead, while a shopping mall fire in Jilin killed 53 people in 2004. In some cases owners or company officials have been arrested as a result of workplace accidents. No arrests were immediately reported and Xinhua said an investigation into the cause had begun. Company representatives could not be reached for comment. Meanwhile, Chinese President Xi Jinping reached Costa Rica where he was to meet the president and other top officials Monday, as Beijing boosts its profile in a region long considered America's backyard.

Arriving in San Jose the night before, Xi said expanding cooperation with the Central American country will help both countries as well as contribute to world peace, China's state news agency Xinhua reported. Xi's packed schedule starts with a meeting with President Laura Chinchilla, where the two leaders are expected to sign several cooperation agreements.

He will also visit the Legislative Assembly and be presented with the keys to the city by San Jose mayor Johnny Araya.

Xi and his wife Peng Liyuan, a soprano singer who has stolen the spotlight during the trip, will later travel to a rural village near the capital before attending a gala dinner hosted by Chinchilla.

Xi arrived in Costa Rica -- the only country that has diplomatic relations with the Asian giant in Central America, where most countries align with Taiwan -- after a three-day stop in oil-rich, English-speaking Trinidad and Tobago, in the first ever visit to Port of Spain by a Chinese president.

US Vice President Joe Biden had visited just days before for a summit with Caribbean basin leaders. The Chinese president focused on trade and energy issues in talks with Caribbean leaders.

"What I found so impressive in the president of China is that he treated the leaders of small Caribbean nations no differently to how he would treat the president of United States" or Britain's leader, Bahamas Prime Minister Perry Christie said.