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As Greece's stock market plunges and borrowing costs soar, analysts warned the country could be facing its "Lehman moment" as it faces bankruptcy and more financial chaos.
Greek bank stocks fell dramatically on Tuesday and its borrowing costs rose sharply following news that European Central Bank (ECB) staff were mulling contingency plans for both an "orderly" and "disorderly" default by Greece, sources told CNBC.
A default could lead to Greece leaving the euro zone—something that closely-watched investor Mark Mobius said could herald the "beginning of the end" of the single currency bloc.
"If there was an exit of Greece from the euro, that would be an amazing event for Europe. It would mean the beginning of the end and that would not be a happy picture," Mobius, executive chairman at Templeton Emerging Markets Group, told CNBC.
Markets are also nervous—the yield on Greece's benchmark ten-year bonds rose to 13.619 percent Tuesday, up from 13.334 percent at the open. Meanwhile, as investors digested news of ECB staff mulling plans to curtail bank funding, shares of the National Bank of Greece fell 8.2 percent, Piraeus Bank slipped 11.2 percent and Alpha bank was 3.8 percent down.
Further weighing on market sentiment was the news on Monday that the Greek government had ordered state bodies to send idle cash reserves to the country's central bank as it scrambled to cover its funding needs.
Greece faces further debt repayments to the International Monetary Fund (IMF) and ECB in the coming months, as well as its own domestic wages and pensions bill, and could struggle to meet its debt obligations.
Eurostat reported on Tuesday that Greece's debt-to-GDP ratio was 177.1 percent at the end of 2014, the highest in the European Union.
The ECB has keenly sought to downplay the chances of Greece leaving the euro zone, with central bank chief Mario Draghi saying he was not even considering such an eventuality. While on Monday, ECB Governing Council member Ewald Nowotny told CNBC that a Greek exit would have less impact now than it would have had two years ago.
However, Tuesday's news signals that officials were considering all eventualities in the ongoing crisis.
Greece has received two international bailouts under the auspices of the ECB, IMF and European Commission, worth a combined 240 billion euros ($256 billion). Its second bailout was extended by four months in February in order to give the Greek government more time to enact reforms. Those reforms are still under discussion, however, and a last tranche of much-needed aid has not been released to Greece as a result.
As concrete reform plans remain elusive, one analyst said that Greece could be heading for its own "Lehman moment," referring to the bankruptcy of U.S. financial firm Lehman Brothers, which is widely thought to mark the start of the global financial crisis.
"Time is not on (Greece's) side," Naeem Aslam, chief market analyst at Ava Trade, said in a note Tuesday.
"There is only one beat playing and it's keeps on getting louder—that Greece will default on its debt and (there is) a strong possibility exist that they can be kicked out of the euro. We maintain our view that such an activity cannot be without its consequence and could bring a much bigger episode of uncertainty than the Lehman crisis."
As the impasse over reforms between the Greek government—which opposes introducing more austerity measures—and the bodies overseeing its bailout program continues, BCS Financial Group's Edmund Shing warned Greece was playing with fire.
"You wonder if the Greek government actually really understand the risks and the fire that they're playing with in pushing to the brink, it could be so easy for them to go too far," the global equity portfolio manager told CNBC Tuesday.
Read MoreWhat would a Greekdefault look like?
"I think Mohammed El-Erian (chief economic advisor at Allianz) put it very well when he talked about an accidental exit (of Greece from the euro zone)—not that they mean to leave the euro zone, but actually they might be forced out through an accident of circumstances."
Shing added that Greece needed to compromise during negotiations over its bailout and reforms and that European lenders would be happy to extend an "olive branch" to help Greece if so.
—By CNBC's Holly Ellyatt, follow her on Twitter . Follow us on Twitter: @CNBCWorld