The United States has criticised China after four members of the outlawed Falun Gong spiritual movement were jailed for up to 18 years.

A White House official said Washington called on China to respect the international covenant on civil and political rights which it had signed.

A Beijing court sentenced four Falun Gong organisers to between seven and 18 years on Sunday for using the cult to undermine the law.

The defendants, including a former senior police official, were also accused of leaking state secrets relating to the government campaign against the sect.

The trial is the government's most significant prosecution against the group since it was banned.

Li Chang and Wang Zhiwen were sentenced to 18 and 16 years - among the harshest sentences given to political or religious dissenters in China this decade - while Ji Liewu and Yao Jie were sentenced to 12 and seven years.

The four were Communist Party members holding positions of influence in government or business.

Government officials have described the sect as the biggest threat to Chinese society for decades.

China banned Falun Gong five months ago. Since then thousands of their members have been detained.

Falun Gong activists in the US condemned the proceeding as a "show trial," that proved that "in this day and age, there is no rule of law and spiritual freedom in China".

Tight security

Police guarded the courtroom building to prevent protests, while other officers questioned passers-by outside the Beijing court.

Relatives of the defendants were also detained ahead of the court hearing, according to a Falun Gong member.

Police told foreign reporters at the courthouse that their presence was a violation of regulations controlling newsgathering and ordered them to leave.

There was no sign of protesters near the court but in Tiananmen Square about 20 people were reportedly detained by police.

Falun Gong members have staged frequent protests in the square since the ban on their group was announced in July.