Jennifer Sinco Kelleher, File, Associated Press
In this July 1, 2015, file photo, protesters hold their hands in the shape of a mountain to symbolize protecting Mauna Kea during a news conference in Honolulu. The protesters gathered for a news conference on their efforts to block the construction of the Thirty Meter Telescope atop Mauna Kea. Seven people protesting a giant telescope atop Mauna Kea have been arrested for defying an emergency rule created to prevent camping on the mountain that is held sacred by Native Hawaiians. The arrests early Friday, July 31, 2015, are the first enforcement efforts since the land board approved the rule July 10.

HONOLULU — Thousands of astronomers from around the world are meeting in Honolulu at a time when telescope construction is a sensitive issue in the state.

Protests are happening at telescopes atop two mountains held sacred by many Native Hawaiians, and some participants were arrested Friday.

The International Astronomical Union's general assembly starts Monday, and organizers and police are bracing for demonstrations.

The protests gained momentum last year when workers on the Big Island tried to start constructing one of the world's largest telescopes. Protests also have spread to a telescope being built on Maui as people demonstrate over issues such as development and religious rights.

Hawaii News Now reports at least 20 people were arrested Friday while trying to block a convoy delivering parts for the Maui project.

Seven others were arrested for allegedly defying a rule created to stop people from camping on the Big Island.