Soviet radicals, led by new Russian President Boris Yeltsin, plan to push the process of reforming the moribund national economy far beyond the gentle transition to market economics proposed by President Mikhail Gorbachev.

In a country where traditional left and right economics have been turned on their heads, pro-free market radicals and conservative communists alike have attacked Mr. Gorbachev's plans.Since its unveiling late last month, his vision of a gradual move to a ''regulated market economy" and associated price rises for food and other goods has been hammered from all sides.

Conservatives, backed by the official trade unions, say it will leave the

average citizen undefended. Radicals like Mr. Yeltsin say it provides too little, too late.

Economist Pavel Bunich called it "shock without therapy."

Instead of the hesitant Gorbachev approach, Yeltsin backers would abandon state monopolies and sell them to their employees - aiming to give a personal incentive in repairing the economy.

The stunning election of Mr. Yeltsin by the Russian parliament, in defiance of Mr. Gorbachev's wishes, has bolstered the left wing and given reform-minded economists a powerful platform.

"The Russian Federation may become the engine of economic reform," said a Western economic analyst. "Yeltsin and his team could give an impetus to the whole Soviet Union."

Rather than a soft transition to free-market principles, the radicals favor a dramatic and rapid move to the free market and the immediate abandonment of the centrally planned economy.

Yeltsin supporters argue their free-market plans shield the average Soviet worker from the dramatic retail price rises planned by Mr. Gorbachev and involves them more directly in reform.

Their different approaches have set the scene for a titanic struggle between Mr. Yeltsin, riding a wave of popular support, and Mr. Gorbachev, back home after a successful superpower summit in Washington.

Radical opposition to the government plan has coalesced around the Inter- Regional Group of parliamentary deputies, which two weeks ago called for a no-confidence vote over the program. Mr. Yeltsin is its co-chairman and founding member.

The no-confidence motion, proposed by Gennady Filshin, a Siberian economist and IRG member, failed, but swelling opposition has tied up the plan in bitter debate.

Many deputies say the government program - and with it, Prime Minister Nikolai Ryzhkov - is dead in the water.

The local parliaments in the Ukraine and usually docile Byelorussia have vetoed price hikes associated with the government program. Mr. Yeltsin already has denounced the plan as "anti-Russian" and vowed to defeat it.

And Tuesday the national parliament voted again to delay action on the plan, this time until June 12.