Russia's foreign minister opened a Moscow-sponsored peace conference for Syria on Tuesday by saying that time is ripe to end the "painful" conflict the war-torn Arab country. Key Syrian opposition and rebels groups, however, boycotted the gathering which Moscow described as an effort to speed up political settlement for Syria.

Sergey Lavrov's comments were also in sharp contrast with the violence on the ground in Syria, where opposition activists reported more airstrikes on the rebel-held province of Idlib. Also, Turkish troops and Turkey-backed opposition fighters marched deeper into a Kurdish enclave in the country's north.

The Russia-sponsored conference opened in the Black Sea resort of Sochi after a two-hour delay, after some members of rebel groups returned to the airport in protest.

Russia, a key ally of Syrian President Bashar Assad, says it invited 1,600 representatives to the Syrian Congress of National Dialogue, but so far only the government and opposition representatives tolerated by Damascus have shown up. The main Syrian opposition body has boycotted the talks.

Sharp disagreements between those attending the conference were clear, with some interrupting Lavrov's speech by chanting pro and anti-Russian slogans forcing him to say: "Please allow me to continue my speech."

"We can confidently say that all the suitable circumstances to end the painful page in the history of the Syrian people are present," Lavrov said. "There is a dire need for a comprehensive Syrian dialogue for the sake of a comprehensive deal for the Syrian crisis."

Lavrov said that Moscow has worked to have this conference represent more Syrians, adding that "only the Syrian people have the right to determine their future."

Syrian government official Ghassan al-Qalaa told the gathering: "I call you upon in the name of millions of Syrian to have mercy upon our country."

Earlier Tuesday, Russian Foreign Ministry spokesman Artyom Kozhin confirmed earlier reports of some members of the rebel groups returning to the airport in protest.

Last week, U.N.-sponsored talks in Vienna, Austria, ended as in many previous rounds with accusations hurled back and forth to the media between the representatives of the warring sides in Syria.

Opposition figures have said Russia is trying to undermine the U.N.-led peace talks. However, the U.N. Special Envoy for Syria Staffan de Mistura was expected to take part in the Sochi conference, though he hadn't shown up in the conference room Tuesday as the gathering started.

Russia has been steering a separate Syria negotiating track in Astana, Kazakhstan, as well.

The Sochi gathering has also been overshadowed by reports of intense clashes that erupted on a strategic hilltop in northwestern Syria as Kurdish forces tried to enter the area a day after it was captured by Turkish troops.

The main Syrian Kurdish militia, which is fighting in Afrin and controls some 25 percent of Syrian territory, has also declined to attend the conference in Sochi, saying it holds Russia responsible for the Turkish offensive.

Turkish authorities on Tuesday detained eight senior members of a medical association who have spoken out against Ankara's military offensive in Afrin, the country's state-run media reported.

Rasit Tukel, the chief of the Turkish Medical Association, and seven other members were detained in police operations in Ankara and other cities for breach of Turkey's anti-terror laws, Anadolu Agency reported. It said prosecutors had issued warrants for 11 members of the association.

President Recep Tayyip Erdogan has accused the association of betrayal and its members of being "terrorist lovers" after the organization warned of the humanitarian costs of Ankara's operation into the Syrian Kurdish enclave of Afrin, launched on Jan. 20.

Turkey considers the Syrian Kurdish People's Protection Units, or YPG, which it is fighting in Syria an extension of the outlawed Kurdish rebels inside Turkey. As many as 311 people have been detained in the past week in Turkey for allegedly engaging in "terrorist propaganda" through social media postings critical of the military operation.

The Paris-based media watchdog Reporters Without Borders has slammed the detentions as the Turkish government's "witch hunt against critics."

The Syrian Observatory for Human Rights says the operation has so far claimed the lives of 61 civilians in Afrin, three in Turkish towns along the border and five Turkish soldiers.

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Associated Press writers Suzan Fraser in Ankara, Turkey, and Bassem Mroue in Beirut contributed to this report.