Iran warned on Tuesday that it will prosecute five British sailors if it is proven they had "bad intentions" when their 60-foot racing yacht entered its waters, in what Britain says was an innocent case of a vessel accidentally going astray in the Gulf.

London was trying to keep the incident from getting tangled up in politics _ not only in the rancor between Tehran and the West over Iran's nuclear issue but also the country's own internal postelection turmoil, which has pumped up the leadership's fears of foreign plots.

Such tensions have already snarled attempts to free three Americans arrested by Iran this summer after they strayed across the border from Iraq. Washington and their families say the three unintentionally crossed into Iran while hiking, but Tehran _ after investigating them for months _ recently accused them of espionage.

The yacht is the pride of a high-profile racing program sponsored by the king of the tiny Arab island nation of Bahrain, which has been trying to build itself as a financial and sporting powerhouse.

The vessel was on its way from Bahrain to Dubai last Wednesday for the start of its first off-shore race when it had a problem with its propeller, according to Andrew Pindar, whose Team Pindar owns the yacht. It drifted into Iranian waters and was seized by the elite Revolutionary Guard near the Iranian island of Sirri, which lies near the mouth of the narrow Hormuz Strait off Dubai.

"There is certainly no question of any malicious intent on the part of these five young people," British Foreign Secretary David Miliband told reporters in London, saying the entry into Iranian waters was inadvertant.

"This is a human story ... It's got nothing to do with politics, it's got nothing to do with the nuclear enrichment program," Miliband said. "We are keen this be resolved as soon as possible."

But Britain expressed frustration, saying that since the detention a week ago, Iran has not let consular officials see the yachtsmen or confirmed they were being on Sirri, as London believes. The head of Britain's diplomatic service, Peter Ricketts, met with Iran's ambassador Tuesday to call for a "speedy resolution."

London is "approaching this manner in a calm but resolute manner, and aggressive rhetoric will not improve the situation," he said. But the delay in an Iranian explanation was "a matter of increasing concern," the Foreign Office said.

In Tehran, the head of Iranian President Mahmoud Ahmadinejad's office said Iran will prosecute the Britons if they intended to "violate the national security" of Iran.