Developing

UK says informed U.N. chief of more Syria chemical attacks

* New reported attacks in Adra, Daraya and Saraqeb

* Syrian government has denied using chemical weapons

* U.N. investigative team still unable to enter Syria

(Adds diplomat on dates of alleged attacks, Susan Rice,

background)

By Louis Charbonneau

UNITED NATIONS, May 29 (Reuters) - Britain has written to

U.N. Secretary-General Ban Ki-moon about additional suspected

chemical weapons attacks by Syrian government forces in March

and April, British U.N. Ambassador Mark Lyall Grant said on

Wednesday.

"We continue to inform the Secretary-General and Mr.

Sellstrom of any information as, and when, we get it," he said,

referring to the Swedish head of a U.N. chemical weapons

investigation team, Ake Sellstrom.

He declined to provide details, but a U.N. official said on

condition of anonymity that the three specific incidents

referred to in Lyall Grant's letter have been previously

publicized.

One was an alleged attack in Adra near Damascus, which a

Western diplomat said on condition of anonymity took place on

March 24.

In that incident, Syrian opposition campaigners said forces

loyal to President Bashar al-Assad fired what they said were

chemical weapons from multiple rocket launchers at rebel

fighters surrounding an army base in the town of Adra on the

outskirts of Damascus, killing two fighters and wounding 23.

The opposition alleged that Assad's forces used chemical

weapons again in late April in Daraya, a suburb of Damascus, and

in Saraqeb around the same time. The Western diplomat said the

Daraya incident occurred on April 25 and the Saraqeb attack on

April 29.

The government has denied using chemical weapons and has in

turn accused rebels of deploying them in the two-year civil war

that the United Nations says has killed over 80,000 people.

A senior French official said on Monday that France was

testing samples of suspected chemical weapon elements used

against Syrian rebels and smuggled out by reporters from Le

Monde newspaper and will divulge the results in the next few

days.

The opposition Syrian National Coalition said in a statement

last week that forces loyal to Assad used chemical weapons a

second time in Adra in an attack that killed four and injured

50.

INCREASING REPORTS OF CHEMICAL ATTACKS

Syrian Ambassador Bashar Ja'afari did not respond

immediately to a request for comment.

A senior U.N. official said last week that the world body

was receiving increasing reports of the use of chemical weapons

in Syria as the violence escalates.

U.S. Ambassador Susan Rice told reporters that U.S.

officials have twice briefed Sellstrom and his team "including a

few weeks ago in Washington where he had the opportunity to sit

with U.S. experts and to hear our best understanding of the

information available to us at that time."

Sellstrom's team of chemical weapons experts has been ready

for more than a month to enter Syria to investigate the

allegations but has been held up by diplomatic wrangling and

safety concerns.

Ban has urged Syria to give the experts unfettered access to

investigate all alleged chemical arms incidents. But Assad's

government only wants the U.N. team to probe the Aleppo incident

from March, not the alleged December Homs attack. U.N. diplomats

say U.N.-Syria negotiations on access have reached a deadlock.

Britain and France wrote to Ban earlier this year to urge

him to investigate three alleged chemical weapons attacks in the

vicinity of Homs in December and Damascus and Aleppo in March.

Ban has urged Syria to permit Sellstrom's team to investigate

both the Homs and Aleppo incidents.

Earlier this month, Carla Del Ponte, a member of a U.N.

inquiry commission looking at allegations of war crimes in

Syria, said the panel had gathered testimony from casualties and

medical staff indicating that rebel forces had used the banned

nerve agent sarin.

But the commission, which is separate from Sellstrom's

chemical weapons investigation team, quickly issued a statement

distancing itself from Del Ponte's remarks, saying it has

reached no conclusions on whether any side in the Syrian war has

used chemical weapons.

Syria, which is not a member of the anti-chemical weapons

convention, is believed to have one of the world's last

remaining stockpiles of undeclared chemical arms.

(Additional reporting by Mohammed Abbas in London; Editing by

Philip Barbara)