ZURICH (Reuters) - Swiss authorities have charged four Iraqi men with planning attacks and helping Islamic State smuggle followers into Europe, Switzerland's attorney general said on Friday.

One man, described as a member of a forerunner of Islamic State (IS), entered Switzerland at the start of 2012, and "forged plans for attacks," Switzerland's Office of the Attorney General said in a statement.

"The three accused individuals also aided and abetted smuggling further IS followers to Europe, assumed coordination tasks, disseminated propaganda for the actions of the terrorist organisation, gave instructions and also provided operative advice, amongst other things," the official added.

The individuals, aged 29 to 34, were not named.

All face charges of participating or supporting a criminal organisation and preparing an attack as well as entering and exiting Switzerland illegally.

Three of the men have been in custody since their arrest in early 2014 in northeastern Switzerland, the office said in a statement. It did not immediately respond to a request for information on the fourth man.

(Reporting by John Miller; Editing by Andrew Heavens)