* Riyadh accused Iran of encroaching on its oil, gas fields
* Tensions over Gulf boundaries, Saudi Shi'ite unrest, Syria
DUBAI, Nov 20 (Reuters) - Iran accused Saudi Arabia on
Tuesday of conducting exploration activities in prohibited
border areas, hitting back at its major rival for regional
influence after Riyadh complained of Iranian encroachments on
its oil and gas fields in the Gulf.
Separated by 250 km (150 miles) of Gulf waters, Shi'ite
Muslim power Iran and Sunni Muslim-led Saudi Arabia have tense
relations. Riyadh accuses Iran of fomenting unrest among
Shi'ites in its oil-rich Eastern Province, a charge Iran denies,
and the two support opposite sides in Syria's civil war.
"Apparently Saudi Arabia has taken action for exploration
activities in prohibited border areas," Iranian Foreign Ministry
spokesman Ramin Mehmanparast said at his weekly news conference
in Tehran, according to the official news agency IRNA.
"The necessary notices were given, and our country's point
of view and our commitment to border agreements were conveyed to
the Saudi ambassador in Tehran."
Mehmanparast was responding to a question about a Saudi
complaint to the United Nations last week saying that Iran
strayed onto its territory near oil and gas fields in the Gulf.
"We think that any differences can be solved in an
environment of cooperation and with a spirit of partnership and
understanding," Mehmanparast added.
The Saudi ambassador to the United Nations, Abdullah
al-Mualimi, was quoted in the daily newspaper Okaz last week as
saying he had sent a letter to U.N. Secretary General Ban
Ki-moon that "details Iran's breaches of the official
conventions and treaties between it and Saudi Arabia".
INTERCEPTION AT SEA
The letter said two Iranian navy boats had intercepted a
vessel belonging to state-owned oil giant Saudi Aramco, and that
Iranian helicopters flew several times over a gas field at
Hasba.
Mehmanparast said it was the Saudis who were at fault.
"The violation that has taken place was on the part of Saudi
companies and if this issue is to be followed up, they must be
questioned," he said. "The discussion about water border limits
between Iran and Saudi Arabia is subject to international laws
and documents between the two countries."
This month, Iran impounded a Saudi Arabian fishing vessel
that entered its southern territorial waters, according to
Iran's official English-language Press TV.
Last month, Saudi border guards arrested 15 Iranians who
tried to enter Saudi Arabia by boat, Saudi media reported.
Iran has had disputes with other Gulf neighbours as well.
Both Tehran and the United Arab Emirates claim as their own
the three islands of Abu Musa and Greater and Lesser Tunb, which
sit near vital oil shipping channels at the mouth of the
strategic Strait of Hormuz.
Iran has said its sovereignty over the islands is
non-negotiable. Mehmanparast was quoted last month as warning
that Iran would consier downgrading ties with the UAE if it
continued to make the claims, although state television later
denied Tehran was considering such a move.
U.S.-backed Saudi Arabia, the world's No. 1 oil producer,
supports the mainly Sunni Muslim rebels fighting to topple
Syrian President Bashar al-Assad. Iran backs the Syrian leader,
whose Alawite religion is derived from Shi'ite Islam.