* Mockus surges 21 points since last Gallup poll
* Former Bogota mayor would win in June run-off
(Adds details on poll)
BOGOTA, April 28 (Reuters) - Colombian presidential candidates Juan Manuel Santos and Antanas Mockus are tied for May’s election, but independent Mockus would win in a run-off in June, according to a poll released on Wednesday.
Former defense minister Santos won 34.2 percent of intended votes for the ballot with Mockus at 31.6 percent, said the poll by Invamer-Gallup, which had a margin of error of around 3 percent and was conducted with 1,200 eligible voters.
Mockus, who has surged in the race to succeed President Alvaro Uribe, would win 47.9 percent in the June run-off while Santos would get 42.2 percent, the poll said.
Candidates must secure more than 50 percent of the votes to win outright on May 30.
Santos is seen as the heir to Uribe, who remains popular for his war on leftist guerrillas and cocaine traffickers. But Mockus, a two-time Bogota mayor, is attracting voters with his message of continued security with more attention to social problems, corruption and joblessness.
For more on the elections, click on [ID:nCOLOMBIA]
Mockus rose more than 21 points from 10.4 percent he secured in Gallup’s last poll in April while Santos remained stable.
Under Uribe, violence, bombing and kidnapping from Colombia’s long war have eased and foreign investment has flooded into the country, especially in oil and mining.
But his government was also marred by scandals over ties between lawmakers and militia death squads, illegal spying by state agents on his opponents and rights abuses by the armed forces.
Santos, Uribe’s defense minister and member of a wealthy Bogota family, led polls until recently as he is closely associated with Colombia’s security successes. But analysts say he is also inheriting disappointment with the government’s failure to tackle corruption, scandals and economic problems.
Investors expect whoever wins will maintain Uribe’s tough security and free-market policies. Polls show that Colombians are more concerned with unemployment, poverty and economic development than with rebel violence.
Reporting by Luis Jaime Acosta, writing by Patrick Markey; editing by Sandra Maler
Our Standards: The Thomson Reuters Trust Principles.