Washington: The US State Department has urged Americans to “exercise increased caution” when travelling to China after a spate of high-profile detentions.

The new advisory warns of so-called exit bans which prohibit foreign citizens from leaving China. It says the bans have been used “coercively” to “lure individuals” back to the country, the BBC reported on Friday.

It also adds that US citizens have been detained for years and subjected to harassment while under an exit ban.

“US citizens may be detained without access to… consular services or information about their alleged crime,” the advisory reads.

The latest advice also warns of “special restrictions” on those who hold dual US-Chinese citizenship.

It advises travelling on a US passport with a valid Chinese visa and asked officials to notify the US Embassy immediately if one is detained or arrested.

The warning comes as three US citizens were accused of committing “economic crimes” and barred from leaving China in November.

Separately, two Canadian citizens have been detained in China since December as relations between the two countries worsened.

Their detentions followed the arrest of Huawei Chief Financial Officer Meng Wanzhou, who was held in Vancouver at the request of US prosecutors on December 1. She faces extradition to the US to face fraud charges.