"Uncertainty faced by the US government and positive economic data recorded by Indonesia gave strength to the currency," chief researcher of Trust Securities, Reza Priyambada, said.
Reza said the gain recorded by rupiah followed the strengthening of yen and other Asian currencies taking advantage of the partial shutdown of the US government.
However, protracted US shutdown would make market players to shy away from risky assets such as currencies of emerging countries including rupiah, he warned.
Optimism as a result of improvement in the country`s economic data marked with trade surplus in August could be dented by worries over sagging US economy, he said.
Monex Investindo Futures` analyst Zulfirman Basir said in addition swa agreement between Bank Indonesia (BI) and its Chinese counterpart contributed rupiah gain .
The agreement would give greater strength for BI to continue intervention in the financial market to protect rupiah, Basir said.
"However, the currency remains volatile as investors still are wary about the partial shut down of the US government," he said.
Meanwhile, the Jakarta composite share price index rose slightly in the opening trade on Monday amid minimum positive sentiment.
The index of the Indonesian Stock Exchange (BEI) was 0.7 percent higher at 4,392.55 points with the index of 45 mots liquid stocks up 0.11 percent to 733.72 points.
The indexes of the majority market in Asia weakened making the BEI index volatile, Reza said.
He said possible profit taking may hamper the BEI index to extend gain, predicting that the BEI index would hover around 4,380--4,430 point on Monday.
Team of technical analysts of Mandiri Sekuritas said investors are awaiting announcement by Bank Indonesia of its benchmark interest rate (BI rate) this week.
The market also are awaiting the final decision on the the US debt ceiling expected to be announced before Oct 17, 2013, the team said.
Regional markets such as Hang Seng recorded a decline of 0.84 percent in index to 22,943.08 points with Nikkei-225 index down 0.83 percent to 13,909.23 points and that of Straits Times falling 0.01 percent to 3,137.77 points.(*)