MOSCOW — A Russian fighter jet crashed off the Syrian coast on Monday while trying to land on an aging aircraft carrier in the Mediterranean, Russian military officials said.
The Russian Defense Ministry blamed a technical failure for the crash of the jet, a MIG-29, according to a ministry statement carried by the Interfax news agency. The pilot, who was the only one in the jet, ejected safely and was picked up by a rescue team, the statement said.
The ministry’s statement did not specify whether the airplane had crashed on the carrier, the Admiral Kuznetsov, or into water.
In a separate statement, the ministry said that rebels in Aleppo had used chemical weapons in an attack on the Syrian Army, poisoning around 30 of its servicemen.
Russia stationed the Admiral Kuznetsov, its only aircraft carrier, off the Syrian coast last week in what analysts said was the latest attempt by the Kremlin to demonstrate its growing might. Designed in the Soviet era, the warship has had a history of problems. Because its technology is obsolete, analysts say, planes are forced to take off without a full load of fuel and weapons.
The ministry said flight operations from the warship had not been suspended. The aircraft carrier has more than a dozen jets on board that can carry out operations around Syria, including over Aleppo, where Russia has been helping the government of President Bashar al-Assad withstand Islamic militants and opposition forces.
On Monday, President Vladimir V. Putin of Russia and the United States president-elect, Donald J. Trump, discussed Syria in their first telephone conversation.
They agreed to work together in the struggle against their No. 1 common enemy — international terrorism and extremism, according to a statement published by the Kremlin. In that context, they discussed issues related to solving the crisis in Syria.
The chemical attack occurred in eastern Aleppo on Sunday evening, and most of the affected soldiers have been hospitalized, a spokesman for the ministry, Maj. Gen. Igor Konashenkov, said in a statement. Russian specialists took samples on site, which confirmed the presence of poisonous chlorine gas, he said.
“Terrorists in Aleppo are using chlorine against the Syrian Army and civilians more and more often,” General Konashenkov said. “However, the politicians in France and especially Britain, who publicly say they worry about Aleppo, do not see these obvious crimes.”
Russia made similar allegations on Friday, saying white phosphorus and artillery shells filled with chlorine gas had been found at a site in Aleppo from which rebels had retreated. The allegations were rejected by the Syrian National Coalition, an opposition group.
In an agreement brokered by Russia and the United States in 2013, Syria renounced the use of chemical weapons and agreed to destroy its stockpile.
Russia has repeatedly accused rebels of using chemical weapons, while vehemently denying allegations that the Syrian Army uses them. An investigation led by the United Nations concluded in October that Syrian forces had used chlorine bombs at least three times from April 2014 to March 2015. The investigation also found that Islamic State militants had used sulfur mustard in August 2015.
The Russian ambassador to the United Nations, Vitaly I. Churkin, said that the investigation’s findings were “unconvincing” and that Mr. Assad’s government should itself investigate whether it had used chemical weapons.
On Friday, the Organization for the Prohibition of Chemical Weapons, the international chemical weapons watchdog, adopted a statement that said, “Every actor involved in these chemical weapons attacks should be held responsible.”
The Russian ministry has asked the organization to send technical specialists to Syria.
“We hope to see specialists in poisonous substances among these O.P.C.W. representatives, not ‘politicized’ humanitarians, who will give us lectures,” General Konashenkov said.