(Updates with new kidnappings)

July 9 (Reuters) - Four more people have been abducted in the Niger Delta, authorities said on Monday, underscoring insecurity in Nigeria's oil-producing region hours after a 3-year-old British girl was freed by her kidnappers.

About 200 adult expatriates have been kidnapped in the Niger Delta since the start of 2006 and 15 are still being held by various armed groups.

Below is a chronology of some major attacks and kidnappings involving the Nigerian oil industry since President Umaru Yar'Adua was sworn in on May 29.

-- June 3 - Gunmen kidnap six staff of United Company RUSAL, the Russian aluminium giant, in Ikot Abasi in the southeast. The men were working at the Aluminium Smelter Company of Nigeria.

-- June 15 - Gunmen kidnap two Lebanese men, working for Italian firm Stabilini, near Ogara in Delta state.

-- June 16 - Militants release 10 Indian hostages held since June 1. The hostages included at least three senior executives of Indonesian petrochemical company Indorama.

-- June 23 - Four hostages, from Britain, France, the Netherlands and Pakistan, employed by oil services giant Schlumberger are released unharmed. The men were abducted on June 1 from Port Harcourt.

-- June 25 - Two Indian construction workers, kidnapped near Sapele in Delta State on June 15, are freed.

-- July 4 - Armed men attack a Shell facility at Soku and abduct five expatriates, two from New Zealand, one Australian, one Venezuelan and one from Lebanon.

-- July 5 - A 3-year-old British child, Margaret Hill, is abducted in Port Harcourt. She is released on July 8.

-- July 7 - Oil major Royal Dutch Shell said one of its teams had been attacked in Rivers state in the delta and two Nigerian workers taken hostage.

-- July 8 - A Briton was among two foreign workers kidnapped from a production barge near Calabar in Cross River state.

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