Mr Key was due to meet Mr Pinera on Saturday at 10am (NZT) - but that meeting will now happen a day later to enable Mr Pinera to attend the funeral of the late Venezuela President Hugo Chavez.
However, Mr Pinera is expected to return to Chile straight after that funeral for the state dinner being held in Mr Key's honour.
Mr Key said New Zealand will send a representative to the funeral, but had not considered diverting from his Latin America tour to attend himself because of the logistical difficulties given his other functions. Foreign Minister Murray McCully was currently in Egypt and would decide who was best to attend.
"We haven't had a political relationship of any great note with Venezuela. Realistically it's been a trade relationship and that's about it. So it would be an unusual thing to send a Prime Minister under those circumstances.
"We will probably assess what is happening around the region with our counterparts, but in the end the Foreign Minister will decide."
Mr Key said his condolences went to the Chavez family and the people of Venezuela. He said Mr Chavez had a very "left wing agenda" for his country which was widely supported there.
"It's obviously a sad moment for Venezuela and the people of Venezuela, I'm sure they will miss him greatly."
He had not personally met Mr Chavez, but had heard him speak at the United Nations.
"He was no fan of Westernised capitalism, that's for sure."
He did not believe New Zealand's decision to send a representative would upset the United States, which had an acrimonious relationship with Chavez.
Mr Key said Venezuela imported a lot of milk powder from New Zealand and he did not expect that to change.
Mr Key and the trade delegation travelling with him arrived in Bogota, Colombia early this morning and he is due to meet with Colombia's President Juan Manuel Santos today at El Narino Palace.
It is the first time the two have met - and has added significance because it is the first visit by a New Zealand Prime Minister to Colombia.
His first stop for the day was to the renowned exclusive Club El Nogal, which was bombed in 2003. Security at the Club was tight, with armed guards outside and explosives sniffer dogs checking bags as people entered.
Mr Key said he expected to announce that New Zealand will support Colombia's wish to be an OECD country and the discussions would also focus on areas in which the relationship could be deepened, such as agriculture, education and investment.
Colombia had already indicated support for New Zealand's bid for the Security Council seat in 2015.
He said he had enjoyed his meeting yesterday with Mexican President Enrique Pena Nieto, describing him as "thoroughly charming".
However, Mr Key feigned ignorance when asked about the beauty of Mr Pena Nieto's wife - a stunning actress. "I didn't notice," he said, when asked before adding, "Bronagh told me to say that."
- Claire Trevett of the New Zealand Herald in Bogota
