HONG KONG (Reuters) - Hong Kong leader Carrie Lam said on Monday three student activists jailed for their roles in 2014 pro-democracy protests were not political prisoners and unreasonable criticism of the city’s judiciary could damage the rule of law.

A demonstrator holds cardboard jail bars, as he protests of the jailing of student leaders Joshua Wong, Nathan Law and Alex Chow, who were imprisoned for their participation of the 2014 pro-democracy Umbrella Movement, also known as "Occupy Central" protests, in Hong Kong China August 20, 2017. REUTERS/Tyrone Siu

Joshua Wong, 20, Nathan Law, 24 and Alex Chow, 27, were jailed for six to eight months on Thursday for unlawful assembly. They plan to file appeals.

In the largest rally in Hong Kong since the months-long “Umbrella Movement” street protests demanding full democracy three years ago, tens of thousands marched on Sunday to condemn what many called politically motivated jailings.

Hong Kong chief Executive Lam defended the decision of city prosecutors to appeal against earlier non-jail sentences and she denounced accusations of it was politically motivated.

“Some say the people involved are being politically persecuted or they are so-called political prisoners. What they say is entirely incorrect,” Lam said.

She said the case was handled according to the law, and while the government would do its best to defend people’s freedom of demonstration, anyone who broke the law would have to face the consequences.

In response to a Reuters report that said Secretary of Justice Rimsky Yuen had overruled other legal officials when they advised against pursuing prison terms for the three activists, Lam said she had no information about that.

But she said it was normal for officials to have different opinions and some criticism of Yuen had been “very unfair”.

Hong Kong became a British colony in the 19th century and returned to Chinese rule in 1997 under a “one country, two systems” formula which guarantees it wide-ranging autonomy, including an independent judiciary and freedom of speech, for at least 50 years.

But many residents fear increasing interference by the mainland government is eroding freedoms.

The jailing of the young activists has attracted international attention.

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A spokeswoman for the U.S. Consulate General Hong Kong and Macau, Kristin Haworth, expressed “concern” over the government’s decision to seek tougher sentences.

German Human Rights Commissioner Bärbel Kofler said they were “particularly concerned about the decidedly political wording of the judgment that gives rise to doubts about judicial independence”.

Britain’s Foreign and Commonwealth Office said it hoped the sentences would not discourage “legitimate protest”, while the European Union said it would follow developments closely.

‘CROSSED THE LINE’

Lam said any assertion that the court was politically biased was “irresponsible”.

“I express great regret over how certain people unreasonably attacked the courts, the entire judiciary, or the judges of the court of appeal due to their dissatisfaction to the court’s sentence or to their different opinions,” Lam said.

“What they damage is not just individual judges, but they also affect Hong Kong’s judicial independence, and the spirit of the rule of law that we greatly treasure.”

In Beijing, Chinese Foreign Ministry spokeswoman Hua Chunying, asked about foreign criticism of the jailing of the activists, said they had “crossed the line of the law”.

Countries should not have double standards on the issue of respecting the law, she said.

“We hope that all sides can respect the handling of the case in accordance with the law by the Hong Kong court and respect Hong Kong’s judicial independence,” she said.

Lam, who was selected by a 1,200-strong committee stacked with Beijing loyalists in the city of 7.3 million, took the helm on July 1, when Chinese President Xi Jinping witnessed her swearing in upon the 20th anniversary of the city’s handover from British to Chinese rule.

She has vowed to heal social divisions, a quest critics say will be difficult after a series of controversies, including government-led court cases that ended up expelling a total of six democratically elected city lawmakers.

Lam told Reuters last month in her first foreign media interview since taking office she would stand by the people of Hong Kong if their core values were being undermined.