MOSCOW (AP) _ Seeking to calm his unruly administration after months of political backstabbing, President Boris Yeltsin picked a low-key politician as his new security chief on Saturday.

Ivan Rybkin, a former speaker of parliament, seems the antithesis of Alexander Lebed, the maverick ex-general fired for trying to take too much control.

Yeltsin's choice appeared designed to bring a conciliatory, pragmatic figure into a Kremlin riven by infighting since the president retreated to a government rest house outside Moscow to await heart surgery.

``During his two years as Duma speaker, (Rybkin) became a symbol of obedience to Yeltsin,'' said Andrei Piontkowsky, director of the Strategic Studies Center, an independent think tank in Moscow.

``The main consideration for Yeltsin, after so unpredictable and defiant a person as Lebed, was to name a person whom he can trust completely.''

Lebed panned the appointment of Rybkin, predicting he ``will behave in the same way as in the State Duma, when deputies were fighting in the hall while he calmly pontificated from his chair.''

``The Security Council will turn into a peaceful bureaucratic office of which no one will hear and no one will know,'' Lebed told the Interfax news agency.

Yeltsin, unlikely to return to full-time work before the end of the year, moved decisively in recent days to halt the feuding that gave the appearance of a government sliding into disarray during his absence.

Yeltsin and Rybkin held a 30-minute meeting Saturday at the Barvikha sanatorium, during which the president took a dig at the ousted Lebed, whose bid for greater authority put him in constant conflict with other top officials.

The president called on Rybkin to act ``within the bounds of the powers given to the Security Council by the president,'' Yeltsin was quoted by a spokesman as saying.

Yeltsin's decree also named Rybkin the president's chief representative in negotiations with separatist rebels in Chechnya. A separate decree Saturday dismissed Lebed from that position. Lebed, ousted Thursday as security chief, negotiated a truce with the Chechen rebels in August.

Rybkin said he planned to uphold ``the peaceful settlement in the Chechen republic.''

``I think very difficult work has been done, and it should be continued,'' he told the ITAR-Tass news agency.

Rybkin, a former Communist Party official who turns 50 on Sunday, was serving as chairman of the president's Political Advisory Council before his appointment.

Unlike Lebed, a retired paratroop general who only entered politics last year, Rybkin is a veteran politician who never has held a senior position in the military or security services.

He became speaker of parliament's lower house, the State Duma, in 1994 and won re-election to parliament as an independent last December. He lost the speaker's job when Communists made the strongest overall showing in the balloting.

As secretary of the Russian Security Council, Rybkin's official role will be that of an adviser and he will not have direct authority over the security services.

The strong-willed and outspoken Lebed had used the post as a platform for his own political ambitions. And while Yeltsin appears to have bought himself a respite by firing him, the dismissed national security chief openly aspires to the presidency and is giving every appearance of already running for the job.

Before seeing a play Friday night about Ivan the Terrible, one of the most feared rulers in Russian history, Lebed joked that he was attending the performance ``so I can learn to govern.'' On leaving the Moscow theater, he quipped that the play had taught him how not to govern.

Yeltsin's opponents backed the president's decision to fire Lebed, reflecting how nearly all the political parties regard the pugnacious ex-paratrooper as a major political and electoral threat to their own fortunes.

Lebed was fired just a day after Interior Minister Anatoly Kulikov, his bitter rival for authority in security decisions, accused him of plotting to form his own army so he could seize power. No evidence has surfaced to back the sensational charge.

Yeltsin's second term, which began in August, lasts until 2000. But with multiple bypass surgery set for next month, jockeying for position has begun among those who presume he won't finish out the term.