* Lavrov meets Kerry in Berlin for talks
* Says Kerry understands seriousness of Syria crisis
* Moscow says Washington must lean on opposition to start talks (Updates with details from meeting)
By Gabriela Baczynska and Arshad Mohammed
MOSCOW/ BERLIN Feb 26 (Reuters) - Russia called on the United States on Tuesday to press the Syrian opposition to hold direct talks with Damascus, saying President Bashar al-Assad's opponents must appoint negotiators.
The crisis in Syria made up "the bulk of the conversation" between Russian Foreign Minister Sergei Lavrov and U.S. Secretary of State John Kerry at talks in Berlin on Tuesday, U.S. State Department spokeswoman Victoria Nuland said.
After talks she characterised as "really serious and hard-working", Moscow and Washington sounded a rare note of accord over efforts to launch talks to end the nearly two-year-old conflict, in which 70,000 people have been killed.
Lavrov said the new U.S. top diplomat seemed to grasp the gravity of the crisis in Syria and that the former Cold War foes had agreed to do everything in their power "to create the best conditions to facilitate the soonest possible start of a dialogue between the government and the opposition."
He said Russia wanted to see the Syrian opposition name its representatives for talks with the government at a meeting in Rome this week between the Syrian opposition, and Western and regional powers favourable to their cause.
Moscow and Washington have been at loggerheads over whether the Syrian opposition's calls for Assad to step down should be a pre-condition for talks.
Lavrov, ahead of the meeting with Kerry, said he would urge Washington to lean on the Syrian opposition to drop requests for Assad to go, a demand he characterised as "unrealistic".
Russia has been one of Assad's staunchest ally and, with China, has blocked three U.N. Security Council resolutions aimed at mounting pressure on him to end the violence that began with a crackdown on street protests against his rule.
Washington has sided with the Syrian opposition in seeking Assad's removal from power.
Syrian Foreign Minister Walid al-Moualem said in Moscow on Monday that the government was ready for talks, but opposition leaders and rebel commanders insist Assad must go first.
Kerry responded dismissively to Moualem's offer, saying it was hard to understand how people having Scud missiles fired at them would take an offer of dialogue seriously. Syria denies using ballistic missiles in the fighting.
He also appeared to promise more concrete support to Assad's opponents, without saying whether the United States might rethink its earlier aversion to arming or training them.
"We are determined that the Syrian opposition is not going to be dangling in the wind," Kerry said in London on Monday.
Lavrov also signalled on Tuesday that the prospects for direct talks in Syria had receded in the past few days, voicing fears "extremists" now have the upper hand among Assad's foes.
"A few days ago it seemed that conditions for the sides to sit down for talks ... were getting clearer," he said.
"But then came denials of such an approach. It seems extremists, who bet on a military solution to Syria's problems and block initiatives to start dialogue, have for now come to dominate in the ranks of the Syrian opposition, including in the so-called (Syrian) National Coalition."
Western countries and some Arab states have accused Russia, a long-standing arms supplier to Damascus, of shielding Assad.
Moscow has hit back by saying it has worked hard to try to persuade the two sides in Syria to start talks and accusing its Western allies of failing to do enough to support those efforts.
It also says support for the rebels plays into the hands of militant Islamists, a theme Assad himself often evokes. (Additional reporting and writing by Alissa de Carbonnel; Editing by Jon Hemming)