The quake struck 115km (70 miles) north-east of the city of Concepcion
Specialist teams from British charities are being sent to Chile after a massive earthquake in the South American country left at least 700 people dead.
Prime Minster Gordon Brown said Britain would do whatever it could to help.
Save the Children has made an urgent appeal for donations while Oxfam has sent experts to the scene.
British diplomats are working to locate and contact UK nationals in Chile. No British casualties have yet been reported.
Foreign Secretary David Miliband said the efforts of the British ambassador to Chile and his team were being hampered by significant communications difficulties.
Worried UK-based relatives have been contacting Chile's embassy in London.
Rafael Moreno, the Chilean ambassador, said: "One girl studying for a degree in London phoned me because her family is on the spot where the earthquake reached almost nine.
"She was in tears, so I calmed her down and told her I will personally do research about the family and I will call her as soon as I have information."
Oxfam is sending a team of water engineers and logisticians from Colombia and is also contacting partner organisations in Chile so that the humanitarian response is as fast as possible.
Jeremy Loveless, Oxfam's deputy humanitarian director, said: "Chile is a developed country with a very capable government and while it is unlikely that this disaster will be as severe as what we saw last month in Haiti, we want to be in place to help as soon as possible."
A spokesman for Save the Children said: "We are assessing the situation and preparing to mobilise teams to support our partners working on the ground."
The charity is also working in Haiti following the earthquake which left thousands dead there in January.
Matt Wingate, emergencies adviser for the charity, said: "It's a challenging situation to have two in the same region so quickly after one another."
The British Red Cross released £50,000 from its Disaster Fund to support the response of the Chilean Red Cross.
Pete Garratt, British Red Cross disaster relief manager, said: "We anticipate the situation in the worst affected areas closer to the epicentre to be much more serious.
"Our fear is that this quake will have had large scale impact.
"The Chilean Red Cross are experienced in reacting to natural disasters and we are making this immediate release of funds to support their relief efforts."