Two of the six Maltese climbers who left Malta on Boxing Day to trek up Mount Aconcagua in Argentina successfully summitted the highest mountain in the Southern Hemisphere last Tuesday.

Team leader Marco Cremona, a water and environmental engineer, reached the 6,962-metre-high summit in the afternoon while Gregory Attard conquered the mountain 45 minutes later. Both carried the Maltese flag to the top.

In an e-mail Mr Cremona sent to his elated girlfriend Joanne Muscat the minute they descended the mountain, he explained that the four other members of the Maltese team - Alec Sultana, a doctor, technician Martin Farrugia, teacher Carmel Hili, and businessman Natal Falzon - had to abandon their summit attempt because of fatigue and time constraints.

"All members of the team managed to reach the base of the dreaded Canaleta, a 300-metre high slope, the last obstacle to the summit," he wrote.

The duo summitted the mountain a day earlier than originally planned because of gale force wind warnings above 5,000 metres. On Tuesday, at 5 a.m in pitch darkness and in temperatures of -20 degrees Celcius, they set off directly for the summit from Base Camp 2 at 5,560 metres instead of the standard Base Camp 3 at 5,930 metres (there are seven camp sites along the route).

"This added three to four hours' trekking time to the eight to nine hours normally allocated for summit day," Mr Cremona explained.

"We had to dig deep into our energy reserves to make it to the base of the Canaleta in good time for the summit attempt. No other groups managed to summit on Wednesday due to 100 k/ph winds."

The trekkers, all experienced Kilimanjaro Challenge climbers, returned to Mendoza province on Thursday. Mr Cremona said they were in good shape and in very high spirits. Mr Cremona and two other members of the team return to Malta on Friday.