JERUSALEM, Jan 30 (Reuters) - The Israeli shekel fell against the U.S. dollar for the fourth straight day on Monday, adding to declines that analysts have tied to the government's proposed changes to the judicial system.

The shekel was down 0.9% to 3.47 in afternoon trade against the dollar after reaching 3.488 earlier in the day.

The currency had strengthened for much of January but started to decline from a four-month high of 3.37 last week. This coincided with economist warnings that a proposed legal shake-up could impact investor confidence as well as massive street protests.

Israeli Prime Minister Benjamin Netanyahu defended his government's bid to attain stronger political control over bench appointments while weakening the Supreme Court's ability to rule against legislation or policy.

He said late Sunday night that groups opposing his proposed changes were trying to scare off investors.

"We made Israeli a solid free market economy. The institutions are strong. Before the reforms it is strong and after the reforms it will be even stronger," Netanyahu said.

The Bank of Israel and Finance Ministry declined to comment on the recent slide in the exchange rate. (Reporting by Ari Rabinovitch and Steven Scheer Editing by Mark Potter)