* Government says speed needed to maintain support for talks
* Rebels blame government for slow pace, offer proposals
* Three previous peace attempts failed
By Jeff Franks and Rosa Tania Valdés
HAVANA, Jan 14 (Reuters) - Representatives of the Colombian government and Marxist-led FARC rebels reconvened in Havana on Monday for a third round of peace talks that the government says need to start moving faster.
The two sides began negotiating an end to their bloody, half-century-old conflict on Nov. 19, but so far have only agreed on procedural issues and are returning from a three-week break over the holidays.
Colombian President Juan Manuel Santos says he wants the process wrapped up by next November, but the rebels have said reaching a peace accord cannot be rushed.
They are trying to end a conflict that began in 1964 with the founding of the FARC, or Revolutionary Armed Forces of Colombia, and in which tens of thousands of people have died and millions more have been displaced.
Upon arrival at the talks on Monday, lead government negotiator Humberto de la Calle called for more speed, saying the talks must move ahead at a "new pace" to maintain the support of the Colombian people.
"The important thing is that during these rounds the pace changes, that we enter with new energy this year so that here in Havana we reach agreement rapidly," he told reporters outside the convention center where the negotiations are being held.
"The people want to see an efficient, dignified, rapid (and) serious process," said de la Calle, a former vice president of Colombia.
With Norway and Cuba acting as guarantors, the government and FARC are following an agenda addressing the basic issues of the conflict, among them rural development, the FARC's involvement in the illicit drug trade, the political and legal future of the group and restitution for the war's victims.
They began with rural development and remain on that topic.
The FARC, founded as a communist agrarian movement to fight Colombia's long history of social inequality and concentration of land ownership, accused the government of slowing the talks by not offering firm proposals necessary to end the conflict.
The government delegation, it said in a communique, "must demonstrate will to advance, putting on the table clear proposals that indicate to the country the government will not prolong indefinitely the solutions" to the problems.
It issued a 10-point proposal for rural development that included its traditional demands for land reform and aid for the rural poor, limits to foreign use of land and respect for the environment and indigenous peoples.
"Instead of a lot of rhetoric, we are starting with concrete proposals to discuss," said lead rebel negotiator Ivan Marquez. "We want to arrive quickly at an understanding."
In a joint communique at the end of the last round on Dec. 21, the two sides said the talks were being held "in an atmosphere of respect and constructive spirit," but in separate comments it was clear that major differences must be overcome.
De la Calle said then that Colombia's political system and economic model were not being negotiated, but Marquez responded that achieving peace "without a doubt requires changes to the model of society and the anti-democratic political system that in the end is responsible for shameful inequality and exclusion that characterize the Colombian regime."
Marquez said last week that the FARC would end on Jan. 20 a two-month unilateral ceasefire it declared at the start of the talks unless the government agreed to do the same, which it has said it will not do.
Despite the ceasefire, attacks by both sides have continued and Colombian officials say the rebels may be planning a new offensive.
Three previous peace attempts have failed, but President Santos is betting that a decade-long, U.S.-backed offensive has weakened the rebels enough that they will want to end the fighting on the best possible terms.
If peace is not achieved, the FARC still has around 9,000 troops that can continue to inflict damage on Latin America's fourth-largest economy.