Sheik Saqr bin Mohammed Al Qasimi, a ruler in the United Arab Emirates federation and one of the world's longest-reigning monarchs, died Wednesday, state media reported. He was 90.

No immediate details on Al Qasimi's death were given by the state-run news agency WAM. Al Qasimi was succeeded as leader of the Ras al Khaimah emirate — one of seven comprising the UAE — by his son, Sheik Saud Bin Saqr Al Qasimi. Sheik Saud was chosen as crown prince seven years ago, opening a messy family feud with his half brother.

Al Qasimi took control of the northernmost emirate in a bloodless coup in the late 1940s — decades before the United Arab Emirates became a country — as part of a dynasty that has ruled the area since the 18th century.

The emirate is far less developed than Dubai or Abu Dhabi, but it has sought to boost foreign investment recently by launching an airline, developing basic industries such as ceramic production and courting resort developers.

Ras al Khaimah was selected last year to host the America's Cup sailing race, but the event was shifted to Spain after objections from the American entry, BMW-Oracle, which questioned the security for the competition because of proximity to Iran's coastline 60 miles (100 kilometers) away.

Ras al Khaimah has deep trade ties with Iran, but the senior Al Qasimi was also at the center of a territorial dispute with Tehran. He initially refused to join the UAE federation in 1971 until he received guarantees that the new nation would not relinquish its claims to several islands in the Gulf under Iranian control.

After the Sept. 11, 2001 attacks, the emirate was drawn into the international fallout as the birthplace of hijacker Marwan al-Shehhi, who flew United flight 175 into the South Tower of the World Trade Center. According to the 9/11 Commission report, al-Shehhi was the son of a prayer leader at a local mosque and joined the UAE military before moving to Germany, where he later lived with fellow plotters Mohamed Atta and Ramzi Binalshibh.

The line of succession in the emirate has been a simmering dispute since Al Qasimi dumped his eldest son, Sheik Khalid bin Saqr Al Qasimi, as the crown prince in 2003 in favor of Sheik Saud to succeed him as leader of Ras al Khaimah. The emirate's name means "top of the tent" in Arabic in reference to the shape of the peninsula shared by the UAE and Oman.

In recent months, Sheik Khalid has stepped up his efforts to succeed his father, hiring an American public relations firm to press his case and lobby lawmakers for support in Washington.

His associates have raised concerns about what they suggest are uncomfortably close ties between Iran and Ras al Khaimah that could destabilize the region.

He does not, however, possess any authority to block the succession.

Shortly after the ruler's death was announced, Sheik Khalid posted a video tribute on his official web page. He praised his father as a "man of great vision and principle" whose passing "marks the end of an extraordinary chapter in the proud history of Ras al Khaimah."

Federal authorities moved quickly to forestall any challenges to the succession. The Federal Supreme Council, made up of the rulers of each of the UAE's emirates, announced its "full support" for Sheik Saud as Ras al Khaimah's new leader in a statement carried by WAM.

The UAE declared a week of official mourning in which flags will be flown at half staff.

A funeral was planned for Wednesday in Ras al Khaimah.

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