BOGOTA (Reuters) -- An arrest warrant issued by a court in Ecuador for Colombian presidential hopeful Juan Manuel Santos threatens to derail the normalization of diplomatic ties, Colombia's leader Alvaro Uribe said.

Santos, running on a platform of continuing Uribe's market-friendly policies, is in second place behind former Bogota mayor Antanas Mockus, according to the latest poll. The election will be held on May 30.
On Monday, Ecuador's Sucumbios Provincial Court upheld a warrant for Santos' arrest for his role in a 2008 bombing raid against Colombian rebels who had set up camp on Ecuador's side of the border. Santos was Uribe's defense minister at the time.
“This is very serious,” Uribe said in a local radio interview. “We have made every effort to advance the reestablishment of relations with Ecuador and we will continue doing so, but this decision by the Ecuadorean courts affects that process.”
Ecuador's leftist President Rafael Correa broke off relations with Colombia after the March 2008 bombing, which killed at least 24 people including Raul Reyes, the No. 2 commander of the Revolutionary Armed Forces of Colombia, or FARC.
The arrest warrant had been briefly suspended earlier this year before it was reactivated on Monday. Santos is closely associated with Uribe's U.S.-backed crackdown on the Marxist rebels, which has made many parts of the country safer and helped attract international investment.
Drug-running FARC guerrillas often seek shelter in neighboring countries. Correa called the raid a massacre and a violation of sovereignty, but relations had been warming in recent months with both countries naming charges d'affaires in their respective embassies.
Bilateral commerce fell to $1.9 billion last year from $2.3 billion in 2008, due in part to the diplomatic strife.
---------Colombia's former Defense Minister Juan Manuel Santos gestures during an interview with Reuters in Bogota February 10, 2010. (Reuters/John Vizcaino)