SAN CRISTOBAL DE LAS CASAS, Mexico (Reuters) -- A recent
                  military build-up in the troubled southern state of Chiapas could lead to
                  renewed clashes between the army and Zapatista rebels, Mexican left-wing
                  legislators warned.

                  "Militarization has reached new heights in the last few weeks," Gilberto
                  Lopez y Rivas of the leftist Party of the Democratic Revolution told Reuters
                  in an interview late on Tuesday.

                  He said roadblocks and troop movements had increased in recent weeks
                  close to where Zapatista rebels have established themselves since their
                  bloody 10-day uprising more than five years ago.

                  Lopez y Rivas and Jose Luis Lopez Lopez of the Labour Party said they
                  were in the impoverished area as part of an advance mission for the Cocopa
                  peace negotiation group that was set to visit later in the week.

                  Cocopa is a congressional commission that has mediated in the conflict
                  between government and rebels.

                  The two congressmen, who are sympathetic to the Zapatista rebels, said the
                  army might be preparing an attack on the Zapatista base at La Realidad,
                  125 miles (201 km) south of the colonial city of San Cristobal de las Casas.

                  Zapatista rebels staged an armed rebellion against the government on
                  January 1, 1994 to demand improved rights for Mexico's 10 million Indians.

                  A tense truce has held up since the 10-day fight killed about 140 soldiers
                  and rebels. But hundreds more have died in related violence including 45
                  Indians at the hamlet of Acteal in December 1997.

                  Tensions in Chiapas have risen in the past two weeks over plans to build a
                  road that Lopez y Rivas charges would help the army carry out attacks on
                  rebels.

                  "The construction of the road is for strictly military purposes. It is a pretext
                  to install a permanent military camp," Lopez y Rivas said.

                  He said protesters in the town of Amador Hernandez had been tear-gassed
                  by the army and that paramilitary groups armed by the government have
                  harassed a foreign reporter and beaten foreign human rights workers trying
                  to reach the village last week.

                  Government officials say the road is being built in response to demands from
                  local communities and deny that a confrontation had occurred between
                  protesters and the army in Amador Hernandez.

                  Interior Minister Diodoro Carrasco said on Tuesday that the protests would
                  not stop the government from pressing ahead with plans to endow the
                  backward region with infrastructure.

                  "The recent incidents...will not alter the will of the federal government to
                  continue to encourage an intense programme in the social sphere," Carrasco
                  told reporters.

                  Lopez y Rivas said 500 soldiers were camped near Amador Hernandez as
                  part of the road-building project.