YANGON, Myanmar -- A special U.N. envoy failed Saturday to meet or secure the release of opposition leader Aung San Suu Kyi, despite international criticism of her detention and U.S. threats of tighter economic sanctions against Myanmar's ruling junta.
Envoy Razali Ismail, on the second day of his five-day mission, said he was still pressing generals who secreted Suu Kyi to an unknown location following a bloody clash in northern Myanmar nine days ago.
"I am still in the process of making my case," Razali told reporters when asked after the meeting whether he would be allowed to see Suu Kyi.
Razali met for more than an hour with Gen. Khin Nyunt, Myanmar's intelligence chief and third-ranking leader, as well as foreign ministry officials. Khin Nyunt had earlier lashed out at the Nobel Peace Prize winner and her National League for Democracy.
In a speech on the eve of Razali's visit, Khin Nyunt accused the NLD of corruption and of triggering the violence by seeking a confrontation with the government.
Myanmar has not allowed access to Suu Kyi since a May 30 clash involving pro-junta supporters and her followers in which at least four people died, saying only she is unhurt and in custody at "a safe place." Offices of her NLD party have been shut and other opposition members detained.
Exiled opposition figures in Thailand say Suu Kyi may have received head injuries in the violence, which they say left up to 70 people dead.
Adding to criticism from around the world, U.N. Secretary-General Kofi Annan issued a statement saying he is "gravely concerned about the continued incommunicado detention of Daw Aung San Suu Kyi and other leaders of the NLD, and is particularly troubled by reports of injuries suffered by them." Daw is an honorific title.
"He fully expects that his special envoy will be allowed to meet all his interlocutors" and that Suu Kyi and other NLD members "will be released without further delay," it said.
The United States also is demanding Razali access to Suu Kyi and her release.
The Bush administration also said it wants Congress to impose more economic sanctions against Myanmar and was reviewing legislation to prohibit imports from the impoverished country. The United States already has some economic and diplomatic restrictions against Myanmar, including a ban on new investments.
State Department spokesman Richard Boucher said the Bush administration believes the May 30 violence was a premeditated ambush of Suu Kyi's motorcade, which suggests the military government has decided to end efforts at national reconciliation.
Tight media controls and the remote location of the clash have made it difficult to confirm independently what happened. The junta says the violence was sparked when Suu Kyi's motorcade drove through a crowd of thousands of government supporters and denies the government was behind the unrest.
A U.S. Embassy official said American diplomats who visited the site reported seeing homemade weapons that appeared to have been made in advance, suggesting a planned ambush by "government-affiliated thugs."
Accounts from exiled opposition groups say government agitators descended on the unarmed members of Suu Kyi's motorcade, beating many to death and killing others with knives and spears.
British Foreign Office minister Mike O'Brien said Friday he had telephoned Myanmar Deputy Foreign Minister Maung Win to press for access to Suu Kyi, and was told she was unhurt.
Suu Kyi, who won the Nobel Peace Prize for her nonviolent struggle for democracy, spent six years under house arrest in 1989-95. Her party won general elections in 1990 but was blocked by the military from taking power.
Razali in late 2000 brokered reconciliation talks between Suu Kyi and the government, and helped secure her release from another 19 months of house arrest in May 2002. But the dialogue reached a standstill later in the year and relations between the two sides have gradually worsened.
International human rights group Amnesty International said Friday it has received reports that other NLD members have been detained in central and northern Myanmar, and said it is gravely concerned about more than 100 people missing since the violence.