PUERTO PRINCESA Philippines (Reuters) - A Philippine court on Tuesday found 12 Chinese fishermen guilty of illegal fishing in Philippine waters, sending them to jail for six to 12 years, the first convictions since tension between the neighbors flared over rival claims in the South China Sea.

Philippine rangers caught the fishermen after their boat ran aground on Tubbataha Reef in April 2013. The reef is not claimed by China but the jailing of the 12 is likely to put more strain on already tense ties.

A Public Attorney's Office (PAO) defending the men said he would appeal.

"We believe the Chinese fishermen are innocent, they did not intend to go into Philippine territory but was forced by bad weather," the lawyer told reporters.

The fishermen sat quietly listening to the verdict which court staff read in English and translated to Chinese.

The captain was sentenced to prison for 12 years while his men were sentenced to from six to 10 years. Judge Ambrosio de Luna also ordered them to pay a fine of $100,000 (£59,287).

The fishermen were also carrying a cargo of pangolins, which is an endangered mammal, like an anteater, eaten in China.

They had said they were on their way from Indonesia to China when bad weather forced them to take shelter at the reef, and they were not aware they were in Philippine territory.

China claims almost the entire South China Sea, an area believed rich in oil and gas deposits and fishery resources. Brunei, Malaysia, the Philippines, Vietnam and Taiwan also claims the sea where about $5 trillion of ship-borne trade passes every year.

Last year, the Philippines filed an arbitration case against China in The Hague over their rival claims in the sea.

(Additional reporting By Manuel Mogato; Editing by Robert Birsel)