Such an agreement would have a direct impact on the world's largest financial companies, including Barclays PLC, Deutsche Bank AG, HSBC Holdings, J.P. Morgan Chase & Co., and Bank of America Corp. In addition to tougher regulatory standards, these companies and others could face new limits on their ability to pay dividends to shareholders based on their financial footing.

Many bankers had expected the new rules to require them to hold modestly higher cushions against future losses. But officials appear poised to demand larger reserves, which they believe will prevent a future financial crisis, and reserves of higher quality.

Regulators have said new rules will help restore confidence in the global banking system. Banks have warned that such requirements could limit economic growth by crimping their ability to lend. Many bankers had believed their arguments were gaining traction, but the new limits regulators appear close to mandating are stiffer than some had expected in recent days.

Officials from more than two dozen countries met in Switzerland on Tuesday and plan to meet again Sunday, where they could reach the framework for a deal.

The current talks, which remain fluid, would require banks to hold common equity equivalent to about 4.5% to 5% of their assets, the people said. During strong economic times, banks would be required to add an additional 2% to 2.5% of common equity, which they could draw from during times of stress.

Common equity is a type of capital banks raise by issuing common stock, among other things. It is considered one of the strongest types of capital, because its holders often sustain the first losses. If banks don't want to issue more stock to raise common equity, they could be forced to retain more of their earnings. That could put a dent in the dividends banks pay out to investors.

This common equity would become the predominant component of the capital cushion held by banks, known as Tier 1 capital, forcing banks to stop relying on less reliable forms of capital.

Under the plan, Tier 1 requirements are also set to rise to between 5.5% and 6% with an additional 3% buffer. If banks dip below the buffer, they would likely face limits on their operations, including how they pay dividends and their ability to pay large executive compensation packages.

Many bankers had expected the new rules to impose total Tier 1 levels of between 7% and 8%.

Regulators hope to phase in new rules between 2013 and 2018, and it is unclear how many banks might be forced to raise capital to meet the new standards. Some banks might choose to restructure and shed riskier assets from their balance sheets.

In a small concession to banks, global regulators have agreed to allow them to hold some types of "hybrid" capital in their Tier 1 holdings, such as investments in insurance companies and mortgage-servicing arrangements. But officials plan to allow banks to use these types of investments for only 15% of their Tier 1 capital. While that threshold appeared a victory for banks as recently as July, regulators appear likely to offset this by requiring companies to hold more capital overall.

U.S. banks are currently required to hold 6% of Tier 1 capital to be designated as "well capitalized," and if they fall below that threshold they face regulatory penalties. Existing rules don't have a mandatory buffer and also don't reflect the more restrictive definition of capital.

While officials appear optimistic a deal can be struck, they have noted the fragility of the talks. German officials refused to endorse the July agreement because they wanted to wait and see where officials would try and set the actual rates.

Regulators are under pressure to complete an agreement. World leaders have said they want a final deal in place by a November meeting of Group of 20 leading nations in Korea. Officials believe setting global standards would prevent banks from moving to jurisdictions with less-onerous rules, but bankers and regulators have clashed over the economic impact of the rules.

The talks are being led by a global consortium called the Basel Committee on Banking Supervision, and the new rules are known commonly as Basel III.