JERUSALEM, March 4 (Xinhuanet) -- Israeli security forces have beefed up military presence in the West Bank to locate Palestinian militants purportedly behind an anti-Israeli bombing attack, a move deviating from a truce promise declared at an Israeli-Palestinian summit one month ago.

   Israeli security sources said Israel is now hunting all Islamic Jihad members, who are believed to be responsible for a suicide attack in Tel Aviv last week, which killed five Israelis.

   The operation marked a policy shift from the Sharm el-Sheikh understandings, under which Israel announced to limit its arrest operations in the territories only to hunt down those it called "ticking bombs" -- terrorists en route to certain places to carry out attacks, the sources said.

   The Israel Defense Forces (IDF) were also sending troops into Tulkarm, rather than leaving preventive operations to  Palestinian National Authority (PNA) security forces in the West Bank city.

   The IDF said the Tulkarm area had turned into a sort of "bubble" with different security rules, compared with the rest of the West Bank.

   For its part, the PNA arrested on Sunday six Islamic Jihad militants in Tulkarm suspected of involvement in the bombing.

   Israel rejected on Thursday a PNA request to transfer to the Jericho prison four Islamic Jihad men arrested in Tulkarm after the Tel Aviv attack, Israel Radio reported.

   Israel also rejected a Palestinian request earlier this week to allow the transfer of two of the suspects to Jericho.

   Israeli security sources argued the rejection stemmed from the fact that the transfer of security control of Jericho to the PNA had not been completed and Israel was concerned that the two would be set free.

   In security coordination talks between Israel and the Palestinians in recent weeks, the idea of creating a safe haven in Jericho for Palestinian fugitives was discussed.

   In such a scenario, Palestinian militants would be allowed to stay in Jericho, if they promised not to launch attacks and agreed to be subject to the PNA. In return, Israel would make a commitment not to harming them.

   No conclusions have been reached on this issue, nor has there been a decision on the Israeli side on transferring Jericho to Palestinian security control.

   Meanwhile, a series of bombs, including a car bomb, were detonated near IDF troops operating in and around the West Bank city of Nablus early Thursday, causing no injuries but raising fresh concerns for the fragile truce between Israel and the Palestinians.

   The car bomb exploded near IDF soldiers operating next to Joseph's Tomb, after the army allowed Jewish worshipers to pray at the holy site. 

   On Thursday morning, two explosive devices were detonated near troops who were operating in the Balata refugee camp near Nablus, but no one was hurt.

   Gunfire was heard early Friday morning at the Ramallah home of Jamil Tarifi, former PNA minister for civil affairs. There were no casualties, the radio reported. Enditem