Supporters of leftist candidate Andres Manuel Lopez Obrador blockaded Mexico's Treasury Department on Thursday as electoral officials conducted a partial recount of the disputed presidential election.

Meanwhile, the Federal Electoral Institute levied some $6.7 million in fines on all five parties that fielded candidates, citing errors or irregularities in their 2005 financial reports. Lopez Obrador's Democratic Revolution Party got the biggest penalty, $2.9 million, while the ruling National Action Party was fined $1.2 million.

Electoral official Andres Albo Marquez said the fines reflected the number and seriousness of the parties' violations. Officials said without elaborating that they found the reports lacked details on how campaign funds were spent.

CountryWatch: Mexico

Initial results gave conservative Felipe Calderon of National Action an advantage of 240,000 votes — less than 0.6 percent of the total — over Lopez Obrador, who has alleged widespread electoral fraud and is demanding a re-count of all 41 million ballots cast July 2. The former Mexico City mayor's supporters have vowed to continue protests until their demands are met.

The Federal Electoral Tribunal last week ordered a partial recount of 9 percent of the 130,000 polling places, where they deemed problems were evident. The re-count began Wednesday and must conclude by Sunday. The tribunal will review the results and has until Sept. 6 to declare a president-elect , annul the election or take other action.

Lopez Obrador has called on supporters to escalate their protests nationwide. Scores of protesters blocked the Treasury. Aides also called for activists to demonstrate outside the attorney general's office.

President Vicente Fox's spokesman Ruben Aguilar asked Mexicans to respect electoral institutions, a day after officials sifted through the votes while searching for errors or evidence of fraud.

Lopez Obrador's campaign team said vote tally sheets were different from actual votes in about 60 percent of the ballot boxes examined, and that 18 percent had been opened after the elections.

"We don't accept this recount," Lopez Obrador told thousands of supporters in Mexico City's central Zocalo Plaza on Wednesday night.

For more than a week, Lopez Obrador's supporters have been camped along the capital's main Reforma Avenue and the central Zocalo plaza, halting traffic and commerce and trying the patience of many of the 23 million people who live and work in the Mexico City metropolitan area.

Calderon's National Action Party officials said Wednesday their observers found no major irregularities and that a recount in western Jalisco state gave Calderon about 2,000 additional votes.