HANOI (Reuters) - A court in Vietnam sentenced a land rights activist to 20 months in jail on Tuesday for causing public disorder, her lawyer said, jailing her for a second time over a similar offense in a case a top human rights group said should have been dropped.

Can Thi Theu, 54, was found guilty at a half-day trial by a district court in Hanoi, three months after she was arrested for leading protests outside government offices against what she called illegal land seizures.

"This is a very unfair and tragic verdict," said Vo An Don, one of her lawyers, adding that she would appeal.

As the court heard the case, dozens of supporters held signs outside saying "Can Thi Theu is innocent" before police shepherded them away to a waiting bus.

In recent years, a real estate market boom in Vietnam has stirred up protests by small landowners evicted to make way for construction projects. Many complain the evictions are illegal and authorities fail to pay adequate compensation.

The sentence comes at a time when Vietnam's human rights record is in the spotlight, with the jailing and intimidation of activists, bloggers and dissidents showing no sign of abating, despite the country's aggressive pursuit of closer economic and diplomatic ties with the West, most notably the United States and European Union.

Theu was detained on June 10 for causing public disorder. A newspaper run by the Hanoi police said she led people to gather at state offices in the capital many times, raising banners and causing traffic jams.

Theu was freed in July 2015 after serving a 15-month term on charge of opposing officials on duty. Upon her release, she posted a video on YouTube in which she said she had been jailed for protesting against land seizures. The New York-based Human Rights said she was caught filming evictions.

The group called on the Vietnamese authorities to drop all charges against Theu and pursue proper legal reforms "instead of punishing people who protest the loss of their land".

(Editing by Martin Petty)