Striking ferry workers pelted busloads of tourists with rocks and bottles Saturday after mistaking them for strikebreakers, police said. Later, two ferries docked at Dover as the company moved to crush the work stoppage.

Trouble flared early Saturday when five buses carrying ferry passengers drove to the dock behind a police cruiser with flashing lights. Hundreds of pickets, mistaking the tourists for strikebreaking crews, surged through police lines, threw rocks and bottles at the buses and hammered on the windows, police said.About 150 officers moved in and quickly broke up the disturbances after scuffles with pickets.

Dover police Inspector Mervyn Williams said a bus windshield was smashed but no one was hurt. One striker was arrested but was later released without charge.

Police Superintendent Tim O'Connor said the buses were carrying passengers into the ferry terminal for crossings on French and Belgian ships to Calais and Ostend.

"Some of them were schoolchildren," O'Connor said. "They were terrified."

Police quickly restored order, but Sam McCluskie, leader of the 24,400-member National Union of Seamen, said: "I cannot guarantee it will be peaceful for long. I want peace, but these men and women have been frustrated to the extent I will not be able to control them."

The P and O strike and support by other seamen also affected crossings from England and Wales to Ireland and the Isle of Man, and between Scotland and Northern Ireland and the Shetland and Orkney islands.

Later Saturday, two ferries sailed into Dover without incident after crossing the English Channel.

P and O workers are striking to protest the company's plan to cut jobs, lengthen shifts and change work rules to have employees perform more tasks. The company says its must trim its staff so it can compete with the English Channel tunnel connecting England and France, which is set to open in 1992.